EXERCISE AS PART OF CANCER CARE: SCIENTIFIC EVIDENCE WITHIN THE BRAZILIAN CONTEXT

EXERCÍCIO FÍSICO PARA O TRATAMENTO DO CÂNCER: EVIDÊNCIAS CIENTÍFICAS E O CONTEXTO BRASILEIRO

ABSTRACT

It is now well-known that physical activity and exercise are both able to prevent the appearance of different types of cancer, increase survival, improve quality of life and attenuate the adverse effects caused by cancer and its treatment. Therefore, the current recommendation is that every cancer survivor must be encouraged to stay active, begin or keep exercising after the cancer diagnosis, contrary to the recommendation of 20 years ago to “rest and avoid physical efforts”. In fact, physical exercise is now recognized as a reliable, inexpensive, adverse effect-free, safe and relatively simple tool to be incorporated into the context of cancer treatment. However, Brazil has not contributed and is not part of the agenda to make exercise as a standard in cancer care. This literature review aims to present the scientific evidence of the use of physical exercise in the different stages of cancer treatment and the most recent contributions to the development of exercise prescription for people with cancer. In addition, I will discuss the main challenges and future perspectives for the area of exercise oncology, considering the Brazilian context.

Key-words:
Oncology; survival; exercise prescription; adverse effects

RESUMO

Sabe-se hoje que a atividade e o exercício físico são capazes de prevenir o aparecimento de diferentes tipos de câncer, aumentar a sobrevida e a qualidade de vida, além de amenizar os efeitos adversos causados pelo câncer e seu tratamento. Assim, a recomendação atual é que todo indivíduo com câncer deve ser encorajado a manter-se ativo, iniciar a prática de exercícios ou continuar se exercitando após o diagnóstico da doença, ao contrário da recomendação de 20 anos atrás de “descansar e evitar esforços físicos”. De fato, o exercício físico é considerado hoje, uma ferramenta completa, barata, isenta de efeitos colaterais, segura e relativamente simples de ser incorporada no contexto do tratamento do câncer. Entretanto, o Brasil não tem contribuído e não está inserido na agenda para transformar o exercício físico como parte do tratamento oncológico. Esta revisão de literatura tem o objetivo de apresentar as principais evidências científicas sobre uso do exercício físico nas diversas fases do tratamento do câncer e as mais recentes contribuições para o desenvolvimento da prescrição do exercício físico em pacientes oncológicos, além de discutir os principais desafios e perspectivas futuras para a área de exercício físico em oncologia, considerando o contexto brasileiro.

Palavras-chave:
Oncologia; sobrevivência; prescrição de exercício; efeitos adversos

Introduction

Cancer is the second most common cause of death worldwide, a disease with a growing incidence rate. The World Health Organization predicts 29.5 million cases in the world by 2040, an increase of approximately 64% compared to 20181. In Brazil, an estimated 625,000 new cases of cancer were reported in 2020, a 27% increase in the past 10 years2.

In addition to the increase in the number of cases, research studies demonstrate a significant increase in the number of cancer survivals in recent years. Because of technological advances in cancer detection and treatment, along with the identification of modifiable behaviors associated with cancer (smoking, drinking, and lack of physical activity), the number of cancer survivors has increased in recent years1. An estimate calculated in 2019 in the United States shows that the number of cancer survivors has increased by 28% in the last 20 years3. This number is expected to increase to approximately 35% in the next decade4. However, cancer survivors suffer a number of adverse effects caused by the cancer and its treatment, such as cardiovascular dysfunction, neuromuscular issues, reduced physical function, metabolic syndrome, and other problems that increase the morbidity and mortality related to cancer in general5. This means that despite improvements in cancer screening and treatment and in the ensuing increased survival rates, cancer survivors experience significant physical and psychological effects that require long-term health care.

In this context, exercise has been recognized as a promising strategy not only in prevention but also as an adjuvant therapy in cancer treatment. Growing evidence from the past three decades demonstrates that exercise attenuates morbidities and cancer treatment side effects and increases the survival rate of people with cancer6. In fact, the international scientific positions and guidelines from researchers and societies published in the past decade recommend that all people with cancer keep as active as possible and/or get involved in exercise programs in all phases during and after their treatment, regardless of the type and the stage of their disease6^),(7^),(8. Unfortunately, Brazil does not seem to be participating in the international agenda to make exercise a part of oncological treatment. Indeed, many challenges to incorporating exercise as an adjuvant therapy against cancer and its complications are seen in Brazil.

This review aims to present the primary scientific evidence regarding exercise as an adjuvant in the cancer treatment continuum, along with the major recent contributions to the prescription of exercise to cancer survivors. Finally, the review briefly discusses the main challenges and the prospects of the field of exercise oncology within the Brazilian context.

Evidence on the role of exercise in oncology

Evidence from the past three decades demonstrates that exercise may prevent some types of cancer as well as decrease mortality and protect against the toxicity associated with cancer treatment in cancer survivors. I will use an adaptation of the setup proposed by Courneya et al.9 to present the main findings on the protective effect of exercise throughout the three main phases of the cancer treatment continuum: 1) pre-habilitation, 2) during treatment, and 3) post-treatment (Figure 1). It is important to note that although exercise plays an important preventive role against cancer (engaged in before the diagnosis of the disease), its effects are beyond of the scope of this review; I suggest that those interested in these effects read studies from the American College of Sports Medicine10 and the World Cancer Research Foundation11.

Exercise in cancer pre-habilitation

Cancer pre-habilitation denotes the period between the diagnosis and the start of cancer treatment. This period may last days or weeks, depending on the number of exams, access to the laboratory exams required for the disease, and access to health care services. In Brazil, the median time between diagnosis and treatment onset in women with breast cancer who use the public health system (Sistema Único de Saúde, or SUS) was 43 days in 201813; approximately 40% of the breast and prostate cancer treatments through the SUS started 60 days after the diagnosis4. The main aim of exercise in pre-habilitation is to condition or prepare the person for the enormous stress imposed by cancer treatment, in the hopes of mitigating its deleterious physiological and psychological effects. Therefore, it is crucial to establish a baseline and identify a commitment to physical function, as well as to propose an exercise intervention program to minimize the severity of the adverse effects of the cancer treatment and to decrease the incidence of physical dysfunctions in the post-treatment stage14.

Figure 1
Benefits of exercise on complications and adverse effects of cancer treatment in the three phases of the cancer treatment continuum: 1) pre-habilitation, 2) during treatment, and 3) after treatment

Studies have been conducted on the use of exercise in cancer pre-habilitation, using various exercise modalities and protocols for different types of cancer15^),(16^),(17^),(18. A study assessing pre-surgery interventions using exercise for people with lung, prostate, and colorectal cancer reviewed 18 studies with a total of 966 participants who performed resistance, aerobic, and combined exercises (resistance and aerobic) for a median period of 21 days (7-52 days). The authors demonstrated that exercising before surgery led to a significant improvement in urinary (in)continence in people with prostate cancer and enhanced functional walking capacity, cardiorespiratory aptitude, and quality of life in people with all types of cancer studied16. Recently, Stout et al.18 conducted an extensive review of cancer pre-habilitation and found improved cardiorespiratory capacity as a result of exercise, which in turn contributed to improved chances of surgical referral for advanced cancer patients and diminished surgical risk; in addition, it prevented a reduction in their cardiorespiratory capacity and ambulation, which consequently accelerated surgery recovery. In fact, studies have demonstrated that the greater the frequency and duration of the exercise before treatment, the greater the benefits and the lower the treatment cost, since exercise attenuates the occurrence and severity of adverse effects as well as reduces the length of use of health care services15^),(16^),(17^),(18. These data demonstrate that pre-habilitation is critical to successful treatment for cancer survivors.

It is important to note that a diagnosis of cancer results in a significant reduction in physical activity, especially due to the psychological stress arising from the diagnosis and the need to reorganize one’s routine and finances in preparation for treatment19. This decrease in physical activity levels contributes to reduced physical capacity and muscle loss, which are major predictors of mortality during the treatment of various types of cancer20^),(21. Thus, exercise can improve the physical condition, strength, and muscle mass of individuals diagnosed with cancer, in addition to building up the confidence that may help them psychologically face the major life challenge of cancer treatment. However, involving people in exercise programs shortly after their cancer diagnosis seems to be a major challenge in oncology-related exercise18.

Some scientific limitations to pre-habilitation must also be highlighted. The strong results listed above were attained in a limited group of cancer types, and many researchers did not use or did not report a standardized exercise frequency and intensity, which makes comparison and reproducibility difficult. The lack of standardization in the initial evaluation also hinders the proper determination of patient evolution in the exercise program; many studies do not ensure that an initial evaluation is carried out close to the diagnosis. Thus, future studies should aim to develop exercise programs that are specific to each type of cancer in order to prevent or minimize individual dysfunctions. For example, people with breast cancer should develop pectoral, arm, and shoulder muscles, along with neck mobility and strength, since many breast cancer survivors feel pain and have reduced local function as a result of a mastectomy18.

Exercise during cancer treatment

The main cancer treatments are surgery, chemotherapy, radiotherapy, immunotherapy, and hormonal therapy, with chemotherapy and radiotherapy being the most frequently used. In brief, chemotherapy involves the use of one or a set of drugs that prevent or interrupt the proliferation of tumor cells. Radiotherapy uses high-energy particles or waves (such as X-ray, gamma-ray, or a beam of electrons or protons) to destroy or damage cancer cells, with the same objective as chemotherapy. In many cases, a combination of both chemotherapy and radiotherapy is necessary, and they are performed in cycles to be efficiently administered in a time interval that enables people with cancer to adequately recover physically. In initial-stage or locally-advanced cancer, chemotherapy and/or radiotherapy are used as a treatment known as a neoadjuvant strategy in order to shrink tumors before surgery. After surgery, these treatments—known as adjuvant therapy—are used to help prevent cancer recurrence (further information on this and other subjects are presented well in Vieira22).

Although neoadjuvant and adjuvant treatments are effective against cancer, they may cause numerous side effects, including nausea and diarrhea, reduced immune function, fatigue and discomfort, hair loss, lack of appetite, and more. The side effects generally start in the early weeks of treatment, and they negatively affect peoples’ engagement in exercise programs. Some of these effects (such as nausea, diarrhea, hair loss) may disappear shortly after the treatment is completed, while others may remain for weeks or years, including cardiovascular diseases and musculoskeletal and metabolic dysfunctions, such as sarcopenia, neuropathies, and weight gain22⁾ (the persistent effects of exercise on such symptoms will be discussed next). Importantly, as surgery is the primary cancer treatment in many cases, the period referred as “during treatment” can be a post-surgery period. Surgery may produce significant anatomical changes and pain, compromising full movement and the individual’s independence. Thus, numerous systematic reviews and meta-analyses have demonstrated that exercise is tolerable and safe, and when it is performed during cancer treatment, it may partially minimize treatment side effects, in addition to preserving physical function and quality of life23^),(24^),(25^),(26.

Muscle mass, strength, and physical function are three of the most studied physical capacities in cancer survivors who participate in exercise programs. This is particularly relevant given the high mortality of people with cancer cachexia, a syndrome characterized by a quick loss of weight, strength, and muscle mass. A meta-analysis has shown that resistance exercise is effective in increasing muscle mass and strength as well as in reducing body fat in people undergoing neoadjuvant and adjuvant therapy, regardless of the type of treatment23. However, we highlight that unsupervised guided exercises performed at home have shown little or no effect on muscle mass and strength in people with breast and prostate cancer27, in contrast to supervised exercise28^),(29_. These data show the importance of supervised exercise programs to increase and/or maintain muscle mass and strength in cancer survivors during their treatment.

Exercise is also beneficial during treatment because it reduces fatigue and improves psychological aspects, such as anxiety, depression, and health-related quality of life24^),(25. A meta-analysis by Kessels et al.24 demonstrated a clear improvement in cancer-related fatigue indexes as a result of exercise intervention during treatment, especially aerobic and combined exercises, for different types of cancer. They also reported that adherence to any kind of intervention is more important than the intensity of the exercise and that high adherence resulted in greater effects on the reduction of cancer-related fatigue.

The role of exercise in preventing and/or attenuating cardiac dysfunction resulting from cancer treatment has also been reported, especially when the cancer is treated with anthracyclines (a class of chemotherapeutic drug) or with mediastinal irradiation—treatment methods with great cardiotoxicity potential. However, the evidence that exercise minimizes or prevents cancer treatment-induced cardiotoxicity and/or loss of cardiorespiratory function is moderate. One study has demonstrated only a moderate increase in oxygen peak (~2.8 ml/kg/min) in cancer survivors who participated in aerobic training26. However, the numbers and quality of these data are still nascent; for this reason, the protective action of exercise against chemo-/radiotherapy-induced cardiotoxicity is still under debate.

Data on the possible benefits of exercise in response to cancer treatment are also scarce: in a meta-analysis, Bland et al.30 demonstrated that only two studies out of eight reported a beneficial effect of exercise on the chemotherapy completion rate—a relevant indicator, given that receiving the planned chemotherapy doses is related to a greater efficacy of the treatment and survival people with cancer. These data suggest that exercise does not seem to improve tolerability to chemotherapy; however, a thorough interpretation of such findings is limited by the small number of studies and their high heterogeneity.

Perhaps one of the main difficulties reported by researchers with regard to exercise prescription and instruction in individuals undergoing cancer treatment is the relatively low adherence to exercise programs (40-60%)31^),(32^),(33. The side effects of the treatment and the lack of experience of the professionals who prescribe exercises and follow up with people with cancer are significant barriers to adherence to the exercise program34. Kirkham et al.32 propose planning exercise intensity and volume individually (a practice called periodization) based on the chemotherapy program of each pearson; the “chemotherapy-periodization” succeeded in raising adherence to the exercise program by nearly 25%.

A major limitation is that most of the studies presented above were carried out with people with two of the most common types of cancer: breast and prostate. It is unknown whether these results apply to other types of cancer. Furthermore, the effects of exercise on other aspects related to cancer and its treatment—such as peripheral neuropathy induced by chemotherapy, cognitive function, nausea and alteration of the digestive system health, bone health, and other aspects—remain unclear. Thus, it is possible to state that despite great advances in recent years, there is still a long way to go to identifying the main protective effects of exercise in individuals undergoing cancer treatment and to defining protocols.

Exercise after cancer treatment

The end of primary treatment (surgery, chemotherapy, and radiotherapy) is characterized by a significant reduction in the risk and some of the main symptoms of the cancer and its acute side effects, and it is a victory for the medical team and the person with cancer. This phase is generally associated with successful treatment. However, it is important to consider that the end of cancer treatment is also the beginning of a new phase: post-treatment and cancer survivorship. This phase lasts from the end of primary treatment to the end of the people’s life. It is important to consider that, depending on the type and the severity of the cancer, this phase can also be considered a period before the start of a new round of treatment, which is implemented either with the goal of curing and/or preventing progression of the disease or as a palliative aiming to improve the individual’s quality of life by relieving the symptoms and side effects related to the disease.

While some cancer survivors will have a life free of symptoms, most will experience some symptoms and adverse effects as a consequence of the disease and its treatment. Some of the effects appear during treatment and can disappear afterwards, while others may remain for the individual’s entire life. In the period immediately after treatment, from the end of the primary adjuvant treatment up to the first year of recovery, the survivor is generally susceptible to the acute effects of the treatment (chemotherapy, radiotherapy, anti-hormone treatment), which are characterized by the occurrence of fatigue, weakness, lymphedemas (edemas resulting from poor drainage of body fluids, generally due to the removal of lymph nodes during surgery to treat the cancer), and other issues35. As mentioned in the previous section, in some cases the surgical treatment can lead to lasting anatomical changes that may compromise the full range of motion and the individual’s independence. For these reasons, this period is associated with high levels of stress, anxiety, and/or depression5.

Some symptoms and adverse effects do not decrease or disappear over time without specific care. Many cancer survivors live with symptoms such as weakness, cognitive difficulties, sexual dysfunction, loss of sleep quality, loss of muscle mass and strength, and psychological dysfunctions (such as depression), with the effects lasting many years after the treatment ends35. These effects are known as long-term adverse effects. Some of these effects are ‘silent’, such as cardiovascular and hormonal dysfunctions and bone health effects36. Notably, in many cases the survivor will continue to use additional anti-hormone therapy or immunotherapy in the post-treatment period, which can cause new side effects or potentiate the side effects of the anti-cancer treatment.

The main benefits of exercise in the post-treatment phase are summarized in recommendation documents, guidelines, and statements on exercise for cancer survivors that have issued by societies and associations, including the American College of Sports Medicine6, the Australian Association for Exercise and Sports Science7, and the Spanish Society of Oncology8. It is relevant to note that all these documents state that exercise is feasible, safe, and tolerable for cancer survivors. In brief, these documents demonstrate that exercise facilitates physical and mental recovery, prevents and/or mitigates many short- and long-term side effects and associated morbidities, and extends survival and improves quality of life in cancer survivors. Furthermore, such benefits have been found for a variety of cancers, including breast, prostate, colorectal, lung, hematological, head and neck, and gynecological cancers, as well as less common cancer types such as brain, testicle, and pancreas cancers7. In fact, exercise has been considered a complete, inexpensive, side effect-free strategy to help cancer survivors resume their normal routines in the post-treatment period6. Exercise in this phase also plays a preventive role, since it reduces the risk of recurrence, which would lead to a new diagnosis and going through the whole treatment continuum again.

Campbell et al.6 reported strong evidence that specific levels of resistance and combined exercises reduce anxiety, depression, and fatigue symptoms related to cancer and its treatment, as well as reducing lymphedemas and improving the physical function and quality of life in cancer survivors. Exercise can also recover the full range and quality of joint movement and the independence that may be compromised in many cancer survivors. Their study also demonstrated moderate evidence that exercise improves quality of sleep and bone health. Despite poor scientific evidence that exercise prevents cardiotoxicity, peripheral neuropathy, and nausea induced by chemotherapy, as well as improves cognitive function, pain, and sexual function and reduces the risk of falls, investigations have corroborated these findings.

In addition to the benefits described above, cohort studies have reported that individuals who are more active in the post-treatment period have a longer survival rate than less active individuals37. These data corroborate the preliminary results of Phase 2 exploratory studies showing that leukemia and lymphoma cancer survivors engaged in exercise programs have longer survival rates than less-active cancer survivors38^),(39.

The practice: when, how, how much, and where individuals with cancer and cancer survivors should exercise

Although consistent evidence shows the importance of exercise in the different phases of cancer treatment, developing practical recommendations for and methods of exercise prescription for people with cancer and survivors remains a major challenge. The first difficulty is determining when people with cancer must start exercising. As discussed above, people with cancer can benefit from exercising by themselves as soon as they are diagnosed15^),(16^),(17^),(18 and throughout the cancer treatment continuum (Figure 1). Although many doctors and specialists also propose resting during cancer treatment, studies have demonstrated that early adherence to exercise programs leads to significant improvements in bone health and muscle mass compared to people who join an exercise program later40. Such evidence has led the American College of Sports Medicine to recommend that people with cancer join exercise programs as early as possible6. However, an early initiation must also take people’ interests and availabilities into consideration in order to ensure their mental health. Disregarding this aspect may considerably reduce adherence to exercise programs31. It must also be kept in mind that many people with cancer will undergo a post-surgery period, when rest may be an important measure.

Various conditions will determine the indication of the type, the most appropriate place, and the level of supervision of exercise for each people with cancer/survivor. Figure 2 summarizes the most important steps in referring people with cancer/survivors to exercise programs (Figure 2). First, it is strongly recommended that cancer survivors have the support of their doctors before engaging in any exercise program. Although some studies and guidelines suggest that medical consent for the practice of exercise is unnecessary7^),(8—due to claims that the need for consent might become a barrier to its promotion—the interaction between the doctor, the exercise professional, and the person with cancer may increase the safety of, confidence in, and people adherence to the exercise program. In the next step, a general evaluation must be carried out to identify the people’s with cancer and survivor’s health profile and the possible risks involved7^),(41. The initial evaluation may also include a set of physical tests, such as for cardiorespiratory capacity, physical function, strength, body mass composition, and bone health. These tests will be useful in establishing the exercise program conditions and objectives, as well as the baseline of the person’s physical capacity, which is central to determining the program’s success and to reassessments of program objectives. Later, decisions around prescription and level of supervision of exercises must be made in view of the severity of the disease, the adverse effects of the cancer treatment, the presence or absence of morbidity and physical dysfunctions, and the phase of the cancer treatment continuum (Figure 2). These steps can help in the design of an exercise program that will be safe, viable, and effective.

Figure 2
The most important steps in the referral of people with cancer and survivors to exercise programs, considering the need for supervision, and venues recommended according to the level of complications and side effects present

Some guidelines and authors6^),(8 discuss the need for supervision the exercise of people with cancer or survivors who experience little or no cancer treatment adverse effects (e.g., some fatigue, sleep disorder). Although people with cancer and survivors may benefit from general exercise guideline recommendations, studies have demonstrated that those who perform supervised exercises have greater adherence and better results than those who perform self-monitored exercises29^),(42. For this reason, although it is unnecessary, I nevertheless recommend that, when possible, people with cancer and survivors practice professionally supervised exercises, even with no or minimal adverse effects and morbidities (Figure 2).

After the identification of a person health profile, the possible risks involved, and the objectives of the exercise program, professionals and patients must address all the components of the prescription of the exercise program in cancer treatment: modality, intensity, frequency, duration, and progression/periodization. Box 1 summarizes the main general recommendations for each of these components.

Box 1
General recommendations and considerations around the five key elements of an exercise program for cancer survivors

Generally, and whenever possible, all exercise programs should include aerobic and strength exercises, with the priority and focus determined according to the objectives proposed. The exercise should be at least of moderate intensity, when possible, and as the program evolves, more intense sessions should be included. Schwartz et al.47 pointed out that exercises for people with cancer who are still weak or debilitated by cancer and its treatment must start at the minimum volume and intensity and gradually increase according to the people’s tolerance to effort increases. The initial sessions serve to develop aerobic capacity, strength, and motivation, as well as build up engagement for longer exercise periods. Unlike some guidelines6^),(41, which propose three to five weekly sessions of aerobic exercises and one or two sessions of strength exercises, new studies7 propose adopting a multimodal exercise program with aerobic, strength, and flexibility exercises in the same session every other day, avoiding consecutive days. I also indicate here that recent studies have demonstrated that some Eastern movement practices (Yoga, Tai-chi, Qigong) and balance and flexibility exercises improve quality of life and quality of sleep as well as reduce fatigue and anxiety associated with cancer and its treatment44^),(45; thus, these can be included in the exercise program. When it is not possible to participate in an exercise program, people with cancer and survivors must nevertheless remain as active as possible6^),(7^),(8. The recommendation to walk over 10,000 steps a day is also widely shared as being beneficial to the health of members of this population8: it is cited in several documents and studies, including the latest version of the World Health Organization Guidelines on Physical Activity and Sedentary Bahavior41, which for the first time highlights the importance of remaining active when having cancer.

In addition to the recommendations and general considerations on health and physical capacity presented in Table 1, it is crucial that the prescription of exercises to people with cancer and survivors also takes into consideration the particularities of each type of cancer and the side effects caused by the treatment. For example, a mastectomy may result in the removal of parts of muscle tissues important in arm and shoulder movement, resulting in pain and limitation of movement, which must be taken into account during exercise planning42. Likewise, the tempo of exercise progression and the degree of overload between exercise sessions must be guided by the appearance and worsening (or not) of side effects and their symptoms. Some of the conditions and specificities related to cancer, as well as contraindications, risks, and reasons pertinent to interrupting the exercise program, are summarized in Box 2.

Box 2
Conditions and specificities related to the prescription of exercise for individuals with cancer and cancer survivors, as well as care, reasons to interrupt exercise, and contraindications

Finally, it is fundamental to make the people with cancer and cancer survivor the main element in designing and implementing the exercise program. People with cancer and survivors must learn to evaluate and manage the intensity of their efforts and monitor their symptoms; this will enhance the efficiency and safety of the training program46. They should also participate in defining the objectives and designing the exercise program. Their exercise and sports history, preferences, motivations, and sensitivity to effort must also be considered when proposing an exercise program. The most efficient and beneficial exercise program is one that the people with cancer and survivors is both able and willing to do47.

Prospects and trends in the exercise oncology field in the Brazilian context

Despite the scientific development in this field and the exponential increase in the amount of information available on the safety and effectiveness of exercise in promoting health in people with cancer and survivors all over the world, in general, the exercise oncology field seems to be lagging behind in Brazil. This conclusion is based on: 1) the lack of data on the physical activity levels of people with cancer and survivors in Brazil and on oncology professionals’ knowledge of and attitudes toward exercise; 2) the absence of Brazilian clinical trials and cohort studies in the international meta-analyses and the standings of scientific associations on this issue in the world; 3) the lack of guidelines or standings issued by Brazilian medical and scientific associations and societies; 4) the scarcity of professional training courses on exercise oncology; and 5) the small number of programs promoting physical activity and exercise among people with cancer and survivors in Brazil. Thus, necessary actions include those promoting the production of information targeted at cancer survivors and their relatives, the training of health professionals, and the dissemination of physical activity and exercise among people with cancer and survivors.

I argue that the scarcity of training courses and, consequently, of professionals specialized in exercise oncology are the main barriers to the development of this field in Brazil. Thus, training professionals to work with exercise oncology may be one of the field’s main challenges in Brazil in the near future. The training of exercise physiologists, physical therapists, and oncology doctors in exercise oncology should ideally start in undergraduate, specialization, and graduate courses. This measure would have a direct impact on the dissemination of the knowledge and the creation of venues dedicated to people with cancer who need specialized services. Although most cancer survivors may exercise safely in fitness centers and clubs or follow exercise programs by themselves based on guidelines and recommendations, supervised exercise programs are needed for those who suffer treatment side effects and limited physical function, who are weak or debilitated, who have acute associated diseases (cardiopathy, diabetes, bone frailty, etc.), or who do not feel sufficiently secure or motivated. However, such programs are scarce in Brazil and limited to university research projects, university hospitals, and philanthropic entities. In a study conducted in Italy, Avancini et al.34 observed that poor professional training and lack of experience were the main obstacles to the adherence of cancer survivors to exercise programs.

Another challenge is introducing exercise to the context of cancer treatment in Brazil. Programs that popularize science and disseminate information on the safety and benefits of exercise throughout the cancer treatment continuum, especially those targeting oncologist doctors, must be created and implemented. For example, an Australian group has developed implementation plans to bring scientific research and practice closer together51^),(52. Schmitz et al.53 and a group of specialists with the initiative Moving Through Cancer published a schedule up to 2029 to make the practice of exercise a part of oncology by promoting informative campaigns, action policies, and health professional training. Unfortunately, Brazil and Latin America do not take part in this initiative and lack measures for introducing exercise to the oncology field.

I envision the creation of environments that are favorable to promoting the well-being and health of people with cancer and survivors; these have increased in developed countries, but are still mostly lacking in emerging countries like Brazil. This includes production of knowledge in universities and hospitals, the training of health care professionals, and the dissemination of specialized knowledge to people with cancer, cancer survivors and their relatives in order to stimulate the practice of exercise as soon as the diagnosis is confirmed.

Conclusions

The exercise oncology field has evolved quickly in the last 30 years; since the first clinical studies published in the late 1980s, numerous studies have tested various types of exercise and effort intensity levels before, during, and after cancer treatment. These studies have resulted in a significant number of systematic reviews, which have supported the drafting of guidelines and recommendations by multiple scientific associations in various countries. These studies and positions clearly show that physical activity and exercise prevent the development of different types of cancer, increase survival, improve quality of life, and minimize the adverse effects of cancer and its treatment in people with cancer and survivors. Thus, contrary to the recommendation 20 years ago to “rest and avoid physical effort”, the current recommendation is that every individual with cancer must be encouraged to remain active and to start or continue exercising6. The exercise oncology field has advanced to the point that we no longer ask whether people with cancer should exercise but how, how much, when, and where they must exercise. Nevertheless, many gaps remain to be bridged, which keep the recommendations of exercise in oncology at a generic level. New studies and guidelines published in the last five years have made great progress toward individualized exercise prescriptions in oncology.

Unfortunately, Brazil and South America do not seem to be included in the international agenda to make the practice of exercise a part of oncological treatment. Numerous random clinical trials, meta-analyses, and scientific positions from various countries have been published in the last 10 years; however, Brazil’s participation is negligible. Therefore, I consider it urgent to mobilize scientists and society—through scientific associations, medical societies, and philanthropic associations—with the goal of obtaining data (e.g., on the level of physical activity and sedentary behavior in people with cancer and survivors, as well as the level of knowledge), promoting the practice of physical activity among people with cancer and cancer survivors, and developing the exercise oncology field in Brazil.

Referências

• Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A. Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 2018;68(6):394-424. Doi: https://doi.org/10.3322/caac.21492
  » https://doi.org/10.3322/caac.21492
• Instituto Nacional de Câncer José Alencar Gomes da Silva. Estimativa 2020: incidência de câncer no Brasil / Instituto Nacional de Câncer José Alencar Gomes da Silva. Rio de Janeiro: INCA, 2019.
• Siegel RL, Miller KD, Jemal A. Cancer statistics, 2019. CA Cancer J Clin. 2019;69(1):7-34.
• National Cancer Institute. Office of Cancer Survivorship: Statistics; [cited 2021 January 01]. Available from: Available from: https://cancercontrol.cancer.gov/ocs/statistics/statistics.html
  » https://cancercontrol.cancer.gov/ocs/statistics/statistics.html
• Fairman CM, Galvão DA. Exercise oncology from diagnosis to treatment: An overview of outcomes and considerations. In: Schmitz KH (editor). Exercise oncology. 1^st Edition. Cham: Springer; 2020, p. 87-110.
• Campbell KL, Winters-Stone KM, Wiskemann J, May AM, Schwartz AL, Courneya KS, et al. Exercise Guidelines for Cancer Survivors: Consensus Statement from International Multidisciplinary Roundtable. Med Sci Sports Exerc 2019;51(11):2375-90. Doi: https://doi.org/10.1249/MSS.0000000000002116
  » https://doi.org/10.1249/MSS.0000000000002116
• Hayes SC, Newton RU, Spence RR, Galvão DA. The Exercise and Sports Science Australia position statement: Exercise medicine in cancer management. J Sci Med Sport 2019;22(11):1175-99. Doi: https://doi.org/10.1016/j.jsams.2019.05.003
  » https://doi.org/10.1016/j.jsams.2019.05.003
• Pollán M, Casla-Barrio S, Alfaro J, Esteban C, Segui-Palmer MA, Lucia A, et al. Exercise and cancer: a position statement from the Spanish Society of Medical Oncology. Clin Transl Oncol 2020;22(10):1710-29. Doi: https://doi.org/10.1007/s12094-020-02312-y
  » https://doi.org/10.1007/s12094-020-02312-y
• Courneya KS, Friedenreich CM. Framework PEACE: an organizational model for examining physical exercise across the cancer experience. Ann Behav Med 2001;23(4):263-72. Doi: https://doi.org/10.1207/S15324796ABM2304_5
  » https://doi.org/10.1207/S15324796ABM2304_5
• Patel AV, Friedenreich CM, Moore SC, Hayes SC, Silver JK, Campbell KL, et al. American College of Sports Medicine roundtable report on physical activity, sedentary behavior, and cancer prevention and control. Med Sci Sports Exerc 2019 Nov;51(11):2391-402. Doi: https://doi.org/10.1249/MSS.0000000000002117
  » https://doi.org/10.1249/MSS.0000000000002117
• World Cancer Research Fund. Physical activity and the risk of cancer. World Cancer Research Fund Network, 2018
• 2018 Physical Activity Guidelines Advisory Committee. 2018 Physical Activity Guidelines Advisory Committee Scientific Report. Washington, DC: U.S. Department of Health and Human Services, 2018.
• Medeiros GC, Bergmann A, Aguiar SS, Thuler LC. Determinants of the time between breast cancer diagnosis and initiation of treatment in Brazilian women. Cad. Saúde Pública 2015;31(6):1269-82. Doi: https://doi.org/10.1590/0102-311x00048514
  » https://doi.org/10.1590/0102-311x00048514
• Carli F, Silver JK, Feldman LS, McKee A, Gilman S, Gillis C, et al. Surgical prehabilitation in patients with cancer: state-of-the-science and recommendations for future research from a panel of subject matter experts. Phys Med Rehabil Clin N Am 2017;28(1):49-64. Doi: https://doi.org/10.1016/j.pmr.2016.09.002
  » https://doi.org/10.1016/j.pmr.2016.09.002
• Cesario A, Ferri L, Galetta D, Cardaci V, Biscione G, Pasqua F, et al. Pre-operative pulmonary rehabilitation and surgery for lung cancer. Lung Cancer 2007;57(1):118-9. Doi: https://doi.org/10.1016/j.lungcan.2007.03.022
  » https://doi.org/10.1016/j.lungcan.2007.03.022
• Singh F, Newton RU, Galvao DA, Spry N, Baker MK. A systematic review of pre-surgical exercise intervention studies with cancer patients. Surg Oncol 2013;22(2):92-104. Doi: https://doi.org/10.1016/j.suronc.2013.01.004
  » https://doi.org/10.1016/j.suronc.2013.01.004
• Ni HJ, Pudasaini B, Yuan XT, Li HF, Shi L, Yuan P. Exercise training for patients pre- and postsurgically treated for non-small cell lung cancer: a systematic review and meta-analysis. Integr Cancer Ther 2017;16(1):63-73. Doi: https://doi.org/10.1177/1534735416645180
  » https://doi.org/10.1177/1534735416645180
• Stout NL, Silver JK, Baima J, Knowlton SE, Hu X. Prehabilitation: An emerging standard in exercise oncology. In: Schmitz KH (editor). Exercise oncology. 1. ed. Cham: Springer ; 2020, p. 111-142.
• Irwin ML, Crumley D, McTiernan A, Bernstein L, Baumgartner R, Gilliland FD, et al. Physical activity levels before and after a diagnosis of breast carcinoma: the Health, Eating, Activity, and Lifestyle (HEAL) study. Cancer 2003;97(7):1746-57. Doi: https://doi.org/10.1002/cncr.11227
  » https://doi.org/10.1002/cncr.11227
• Kroenke CH, Prado CM, Meyerhardt JA, Weltzien EK, Xiao J, Cespedes Feliciano EM, et al. Muscle radiodensity and mortality in patients with colorectal cancer. Cancer 2018 Jul 15;124 (14):3008-15. Doi: https://doi.org/10.1002/cncr.31405
  » https://doi.org/10.1002/cncr.31405
• Xiao J, Caan BJ, Cespedes Feliciano EM, Meyerhardt JA, Peng PD, et al. Association of low muscle mass and low muscle radiodensity with morbidity and mortality for colon cancer surgery. JAMA Surg 2020;155(10):942-49. Doi: https://doi.org/10.1001/jamasurg.2020.2497
  » https://doi.org/10.1001/jamasurg.2020.2497
• Vieira SC. Oncologia básica para profissionais de saúde. 1. Ed. Teresina: EDUFPI, 2016.
• Padilha CS, Marinello PC, Galvão DA, Newton RU, Borges FH, Frajacomo F, et al. Evaluation of resistance training to improve muscular strength and body composition in cancer patients undergoing neoadjuvant and adjuvant therapy: a meta-analysis. J Cancer Surviv 2017;11(3):339-49. Doi: https://doi.org/10.1007/s11764-016-0592-x
  » https://doi.org/10.1007/s11764-016-0592-x
• Kessels E, Husson O, van der Feltz-Cornelis CM. The effect of exercise on cancer-related fatigue in cancer survivors: a systematic review and meta-analysis. Neuropsychiatr Dis Treat 2018;14:479-94. Doi: https://doi.org/10.2147/NDT.S150464
  » https://doi.org/10.2147/NDT.S150464
• Fairman CM, Zourdos MC, Helms ER, Focht BC. A scientific rationale to improve resistance training prescription in exercise oncology. Sports Med 2017;47(8):1457-65. Doi: https://doi.org/10.1007/s40279-017-0673-7
  » https://doi.org/10.1007/s40279-017-0673-7
• Scott JM, Zabor EC, Schwitzer E, Koelwyn GJ, Adams SC, Nilsen TS, et al. Efficacy of exercise therapy on cardiorespiratory fitness in patients with cancer: a systematic review and metaanalysis. J Clin Oncol 2018;36(22):2297-305. Doi: https://doi.org/10.1200/JCO.2017.77.5809
  » https://doi.org/10.1200/JCO.2017.77.5809
• Demark-Wahnefried W, Case LD, Blackwell K, Marcom PK, Kraus W, Aziz N, et al. Results of a diet/exercise feasibility trial to prevent adverse body composition change in breast cancer patients on adjuvant chemotherapy. Clin Breast Cancer 2008;8(1):70-9. Doi: https://doi.org/10.3816/CBC.2008.n.005
  » https://doi.org/10.3816/CBC.2008.n.005
• Sweegers MG, Altenburg TM, Chinapaw MJ, Kalter J, Verdonck-de Leeuw IM, Courneya KS, et al. Which exercise prescriptions improve quality of life and physical function in patients with cancer during and following treatment? A systematic review and meta-analysis of randomised controlled trials. Br J Sports Med 2018 Apr;52(8):505-513. Doi: https://doi.org/10.1136/bjsports-2017-097891
  » https://doi.org/10.1136/bjsports-2017-097891
• Stout NL, Baima J, Swisher AK, Winters-Stone KM, Welsh J. A systematic review of exercise systematic reviews in the cancer literature (2005-2017). PM R 2017;9(9S2):S347-S384. Doi: https://doi.org/10.1016/j.pmrj.2017.07.074
  » https://doi.org/10.1016/j.pmrj.2017.07.074
• Bland KA, Zadravec K, Landry T, Weller S, Meyers L, Campbell KL. Impact of exercise on chemotherapy completion rate: A systematic review of the evidence and recommendations for future exercise oncology research. Crit Rev Oncol Hematol 2019;136:79-85. Doi: https://doi.org/10.1016/j.critrevonc.2019.02.005
  » https://doi.org/10.1016/j.critrevonc.2019.02.005
• Capozzi LC, McNeely ML, Lau HY, Reimer RA, Giese-Davis J, Fung TS, et al. Patient-reported outcomes, body composition, and nutrition status in patients with head and neck cancer: Results from an exploratory randomized controlled exercise trial. Cancer 2016 5;122(8):1185-200. doi: https://doi.org/10.1002/cncr.29863
  » https://doi.org/10.1002/cncr.29863
• Kirkham AA, Bonsignore A, Bland KA, McKenzie DC, Gelmon KA, VAN Patten CL, et al. Exercise prescription and adherence for breast cancer: One size does not FITT all. Med Sci Sports Exerc 2018;50(2):177-86. Doi: Exercise Prescription and Adherence for Breast Cancer: One Size Does Not FITT All 10.1249/MSS.0000000000001446.
  » https://doi.org/10.1249/MSS.0000000000001446
• Kirkham AA, Bland KA, Zucker DS, Bovard J, Shenkier T, McKenzie DC, et al. "Chemotherapy-periodized" exercise to accommodate for cyclical variation in fatigue. Med Sci Sports Exerc 2020;52(2):278-286. Doi: Exercise Prescription and Adherence for Breast Cancer: One Size Does Not FITT All 10.1249/MSS.0000000000002151.
  » https://doi.org/10.1249/MSS.0000000000002151
• Avancini A, Skroce K, Tregnago D, et al. "Running with cancer": A qualitative study to evaluate barriers and motivations in running for female oncological patients. PLoS One 2020;15(4):e0227846. Doi: https://doi.org/10.1371/journal.pone.0227846
  » https://doi.org/10.1371/journal.pone.0227846
• Gegechkori N, Haines L, Lin JJ. Long-Term and latent side effects of specific cancer types. Med Clin North Am 2017;101(6):1053-73. Doi: https://doi.org/10.1016/j.mcna.2017.06.003
  » https://doi.org/10.1016/j.mcna.2017.06.003
• Gosain R, Miller K. Symptoms and symptom management in long-term cancer survivors. Cancer J 2013;19(5):405-9. Doi: https://doi.org/10.1097/01.PPO.0000434391.11187.c3
  » https://doi.org/10.1097/01.PPO.0000434391.11187.c3
• Li T, Wei S, Shi Y, Pang S, Qin Q, Yin J, et al. The dose-response effect of physical activity on cancer mortality: findings from 71 prospective cohort studies. Br J Sports Med 2016;50(6):339-45. Doi: https://doi.org/10.1136/bjsports-2015-094927
  » https://doi.org/10.1136/bjsports-2015-094927
• Hayes SC, Steele ML, Spence RR, Gordon L, Battistutta D, Bashford J, et al. Exercise following breast cancer: exploratory survival analyses of two randomised, controlled trials. Breast Cancer Res Treat 2018;167(2):505-14. Doi: https://doi.org/10.1007/s10549-017-4541-9
  » https://doi.org/10.1007/s10549-017-4541-9
• Courneya KS, Friedenreich CM, Franco-Villalobos C, Crawford JJ, Chua N, Basi S, et al. Effects of supervised exercise on progression-free survival in lymphoma patients: an exploratory follow-up of the HELP Trial. Cancer Causes Control 2015;26(2):269-76. Doi: https://doi.org/10.1007/s10552-014-0508-x
  » https://doi.org/10.1007/s10552-014-0508-x
• Taaffe DR, Galvão DA, Spry N, Joseph D, Chambers SK, Gardiner RA, et al. Immediate versus delayed exercise in men initiating androgen deprivation: effects on bone density and soft tissue composition. BJU Int 2019;123(2):261-69. Doi: https://doi.org/10.1111/bju.14505
  » https://doi.org/10.1111/bju.14505
• World Health Organization. Global recommendations on physical activity for health. Geneva: World Health Organization, 2020.
• Sweegers MG, Altenburg TM, Brug J, May AM, van Vulpen JK, Aaronson NK, et al. Effects and moderators of exercise on muscle strength, muscle function and aerobic fitness in patients with cancer: a meta-analysis of individual patient data. Br J Sports Med 2019;53(13):812. Doi: https://doi.org/10.1136/bjsports-2018-099191
  » https://doi.org/10.1136/bjsports-2018-099191
• Segal R, Zwaal C, Green E, Tomasone JR, Loblaw A, Petrella T; Exercise for people with cancer: a clinical practice guideline. Curr Oncol 2017;24(1):40-6. Doi: https://doi.org/10.3747/co.24.337610.3747/co.24.3376
  » https://doi.org/10.3747/co.24.337610.3747/co.24.3376
• Cramer H, Lauche R, Klose P, Lange S, Langhorst J, Dobos GJ. Yoga for improving health-related quality of life, mental health and cancer-related symptoms in women diagnosed with breast cancer. Cochrane Database Syst Rev 2017;1(1):CD010802. Doi: https://doi.org/10.1002/14651858.cd010802.pub2
  » https://doi.org/10.1002/14651858.cd010802.pub2
• Smith KB, Pukall CF. An evidence-based review of yoga as a complementary intervention for patients with cancer. Psychooncology 2009;18(5):465-75. Doi: https://doi.org/10.1002/pon.1411
  » https://doi.org/10.1002/pon.1411
• Schwartz AL, Bea JW, Winters-Stone K. Long-Term and late effects of cancer treatments on prescribing physical activity. In: Schmitz KH (editor). Exercise oncology. 1. ed. Cham: Springer ; 2020, p. 267-282
• Campbell KL, Kirkham AA. During infusion Therapy. In: Schmitz KH (editor). Exercise oncology. 1. ed. Cham: Springer; 2020, p. 165-188
• Schmitz KH. Exercise prescription and programs adaptations. In: ACSM's Guide to Exercise and Cancer Survivorship. 1. ed. São Paulo: Editora Phorte; 2015, p. 123 - 156.
• Fabi A, Bhargava R, Fatigoni S, Guglielmo M, Horneber M, Roila F, Weis J, Jordan K, Ripamonti CI; ESMO Guidelines Committee. Cancer-related fatigue: ESMO Clinical Practice Guidelines for diagnosis and treatment. Ann Oncol 2020;31(6):713-23. Doi: https://doi.org/10.1016/j.annonc.2020.02.016
  » https://doi.org/10.1016/j.annonc.2020.02.016
• Morris C, Wonders KY. Concise review on the safety of exercise on symptoms of lymphedema. World J Clin Oncol 2015;6(4):43-4. Doi: https://doi.org/10.5306/wjco.v6.i4.43
  » https://doi.org/10.5306/wjco.v6.i4.43
• Kennedy MA, Bayes S, Newton RU, Zissiadis Y, Spry NA, Taaffe DR, et al. We have the program, what now? Development of an implementation plan to bridge the research-practice gap prevalent in exercise oncology. Int J Behav Nutr Phys Act 2020;17(1):128. Doi: https://doi.org/10.1186/s12966-020-01032-4
  » https://doi.org/10.1186/s12966-020-01032-4
• Kennedy MA, Bayes S, Galvão DA, Singh F, Spry NA, Davis M, et al. If you build it, will they come? Evaluation of a co-located exercise clinic and cancer treatment centre using the RE-AIM framework. Eur J Cancer Care (Engl) 2020;29(4):e13251. Doi: https://doi.org/10.1111/ecc.13251.
  » https://doi.org/10.1111/ecc.13251
• Schmitz KH, Stout NL, Maitin-Shepard M, Campbell A, Schwartz AL, Grimmett C, et al. Moving through cancer: Setting the agenda to make exercise standard in oncology practice. Cancer 2021;127(3):476-84. Doi: https://doi.org/10.1002/cncr.33245.
  » https://doi.org/10.1002/cncr.33245

Publication Dates

• Publication in this collection
  11 Apr 2022
• Date of issue
  2022

History

• Received
  03 Feb 2021
• Reviewed
  31 Mar 2021
• Accepted
  23 June 2021