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Cancer and Exercise. B. Elizabeth Delasobera, MD Sports Medicine Fellow. Outline. The mechanism for how exercise can prevent cancer The evidence for exercise and increased cancer survival The exercise prescription for cancer patients and survivors. Cancer Review.
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Cancer and Exercise B. Elizabeth Delasobera, MD Sports Medicine Fellow
Outline • The mechanism for how exercise can prevent cancer • The evidence for exercise and increased cancer survival • The exercise prescription for cancer patients and survivors
Cancer Review • Excessive, uncontrolled cellular proliferation with potential for metastasis • Symptoms can be local or systemic • Variety of treatments • Surgery, Radiation, Chemotherapy, Immunotherapy • Designed to attempt remission or cure, or for disease control or symptom relief
Mechanism for Cancer Reduction with Exercise • Physical activity lowers levels of biologically available sex hormones • Decreased lifetime exposure to endogenous sex hormones -> decreased risk of hormone-related cancers • Breast, endometrial, ovaries, prostate, testes
Mechanism for Cancer Reduction with Exercise • Exercise decreases endogenous insulin production • Higher levels of circulating insulin linked with several cancers • Exercise associated with decreased levels of IGF • High levels of IGF-1 a/w several cancers (colon, prostate, breast, lung)
Mechanism for Cancer Reduction with Exercise • Adiposity and Cancer Risk • Increased fat associated with increased risk of cancers of colon, kidney, esophagus, endometrium, thyroid, post-menopausal breast • Physical activity decreases colon transit time • Decreases colonic exposure to carcinogens in stool • Level of physical activity inversely related to levels of C-reative protein • NSAID use in physically active • NSAID use appears to decrease colon cancer risk
The Evidence:Exercise and Cancer Risk • Breast Cancer • Invasive Breast Cancer risk decreased by 15%-50% among physically active women • Women < 40yo exercising 4 hrs/week or more during reproductive years had 50% risk reduction • Postmenopausal women with higher rates of recreational activity have lower incidence of breast cancer • Confirmed in over 30 studies in multiple demographic and population groups • Studies focused solely on in situ Breast Cancer have shown similar reductions in risk • Estrogren receptor negative cancer seem to be most reduced with exercise Bernstein L, AACR Education Book 2008:225-231 (2008)
The Evidence:Exercise and Cancer Risk • Breast Cancer • Greatest reduction is risk found with exercise during reproductive years, strenuous activity, at least 5 hours per week • Estrogen receptor-negative Breast Cancer responds better to exercise than receptor-positive cancer • Meta-analysis revealed a dose-response relationship of 6% decrease in relative risk for each additional hour of physical activity per week Monninkhof EM, et al. Epidemiol 2007;18:137–57. Bernstein L, AACR Education Book 2008:225-231 (2008)
The Evidence: Exercise and Cancer Survival • Breast Cancer Survival Meta-Analysis • 24% - 67% reduction in total deaths and 50% reduction in breast cancer recurrence in women who are physically active • Best effect in women who underwent equivalent of brisk walking 3h per week • Effect observed in pre and post-menopausal, overweight and normal weight women, and those with stage I-III disease
The Evidence:Exercise and Cancer Risk • Colon Cancer • 43 out of 51 studies demonstrated decreased risk of colon cancer in the most physically active participants • Risk reduction averaged 40%-50%, up to 70% • Consistent risk reduction despite differing study designs and populations and types of exercise • Greater effect in men vs. women • Hormone supplementation in postmenopausal women also has protective effect • Unclear exercise effect on rectal cancer Bernstein L, AACR Education Book 2008:225-231 (2008) Friedenreich CM, et al. J Nutr 132:3456-3464, 2002.
The Evidence: Exercise and Cancer Survival • Colon cancer survival • 3h per week of moderate physical activity after colon cancer diagnosis: • 39%-59% decreased risk of colon cancer death • 50%-63% decreased risk of total death • Effect essentially unchanged across age, sex, BMI, disease stage, age at diagnosis • Meyerhardt JA, et al. J Clin Oncol 2006;24:3535–41
The Evidence:Exercise and Cancer Prevention • Prostate Cancer • Less consistent data, risk reduction averaged 10% - 30% • Poor understanding of natural history of Prostate Cancer • Exercise can also reduce risk of BPH • Exercise lowers severity of disease and fatalities from prostate cancer • Likely that very high level of exertion early in life needed to influence implicated hormones Bernstein L, AACR Education Book 2008:225-231 (2008) Friedenreich CM, et al. J Nutr 132:3456-3464, 2002.
The Evidence:Exercise and Cancer Prevention • Endometrial Cancer • Strong association with Breast Cancer • Fewer/lower quality studies • Majority still show decreased risk of endometrial cancer with increased physical activity • Risk Reduction varied: 0 – 90%, average 30% - 40% • Majority of studies show dose response effect Bernstein L, AACR Education Book 2008:225-231 (2008) Friedenreich CM, et al. J Nutr 132:3456-3464, 2002.
The Evidence:Exercise and Cancer Prevention • Lung Cancer • Physical activity probably decreases risk of lung cancer, but effect not well-established • Meta-analysis shows 13% risk reduction with moderate recreational physical activity and 30% decreased risk with strenuous activity • Studies may not reflect differences in smoking habits Tardon A, et al. Cancer Causes Control 2005;16:389–97.
The Evidence:Exercise and Cancer Prevention • Limited and/or insufficient evidence: • Ovarian Cancer • Testicular Cancer • Renal Cell Cancer • Pancreatic Cancer • Thyroid Cancer • Melanoma
Survivors and Obesity • Improvements in treatment means more survivors • 11 million cancer survivors in US alone • Obesity and a sedentary lifestyle prevalent among cancer survivors (Irwin ML, BJSM 2009;43:32-38) • Higher than general population • Increases risk of cancer recurrence and death • In breast cancer survivors, obesity assoc w/ 50% increase in cancer recurrence and death (Kroenke CH, et al. J Clin Oncol 2005;23:1370–8) • Cancer survivors die from non-cancer related CVD and DM2 at a higher rate than the general population
So Are Cancer Pts Exercising? • Despite these well documented dramatic effects, the great majority of cancer survivors do not participate in regular physical activity • Many cancer survivors decrease their physical activity after diagnosis • Women with breast cancer exercise, on average, 2 hours less per week 1 year after diagnosis than pre-diagnosis.
Recs for Exercising with Cancer • Goal is to preserve and possibly improve function • Must be individualized • Tailor to level of function • Accommodate for periods of increased fatigue and cycles of treatment • Make exercise an integral part of everyday life
Recs for Exercising with Cancer • 30-50% of breast cancer deaths among post-menopausal women can be attributed to being overweight • Cancer survivors die of non-cancer causes at a higher rate than persons in the general population (CV dz, DM, etc)
Recs for Exercising with Cancer • Special Considerations for Cancer and Exercise: • Cancer treatment can cause osteoporosis; bony metastases may weaken bone = higher risk of pathologic fracture • Be aware of Hickman cathethers, Port-a-caths, other access lines • If platlet count is below 50k, consider risk of bleeding • Consider concomitant effects of CVD and anemia
Recs for Exercising with Cancer • Medications That Can Effect Exercise Tolerance: • Glucocorticoids: may cause muscle weakness and wasting • Growth factors: may cause bone pain • Chemotherapy: may cause anemia, fatigue, and nausea; possibly myopathies and neuropathies • Anthracyclines can cause cardiomyopathy, heart failure and coronary vasospasm • Radiation: may cause skin breakdown, muscle and joint constriction, and cardiopulmonary fibrosis
Recs for Exercising with Cancer • American Cancer Society Recs: • While getting adjuvant treatment recs 3-5 days/week for 20-30 mins tailored to fitness level and tx side effects (ex, walking, resistance training, yoga) • Survivors use ACSM sports prescription guidelines (keep in mind any limitations based on prior slides)
Recs for Exercising with Cancer • Things to Keep in Mind with Return to Sport: • Immunocompromised? (neutropenia, on chemo, etc) • At risk of bleeding? (platlet count, coags, meds) • At risk of CV issues? (meds) • “Neck check”
Summary • Multiple biologic explanations for benefits of exercise with respect to cancer risk reduction and survival • Exercise and Cancer Prevention • Convincing evidence for increased activity and prevention of colon, breast, and prostate cancer • Probable evidence for endometrial and lung cancer • Insufficient evidence for all others
Summary • Exercise and Cancer Survival • Increasing numbers of survivors in population • Decreasing physical activity among survivors • Increased physical activity significantly lowers cancer recurrence and total death in survivors • Exercise Prescription • Must be individualized • Many confounding factors (be aware of meds and side effects) • Keep it simple, make it regular, progress gradually