Physical activity and cancer survivorship.

According to the Centers for Disease Control and Prevention, a cancer survivor is defined as anyone who has been diagnosed with cancer, from the time of diagnosis through the remainder of his or her life.1 It is estimated that there are approximately 14.5 million cancer survivors alive in the United States, and this number is expected to rise to 19 million by 2024.2–4 The increase in the cancer survivor population is largely attributed to improvements in early detection of first malignancies and effective treatment modalities.5 Consequently, the 5-year relative survival rate after cancer diagnosis for all cancers is 68%, which reflects a 19% improvement over the past 2 decades.2 The aging population of the United States also is contributing to the rise in the cancer survivor population since the incidence of most cancers increases with age.6 In fact, it is estimated that nearly 63% of cancer survivors will be 65 years or older by 2020.7,8 The increase in the cancer survivor population parallels the obesity epidemic in the United States, with 69% of adults classified as overweight (body mass index [BMI] ≥25.0 kg/m2) and 35.1% as obese (BMI ≥30.0 kg/m2).9 As a result, most cancer survivors are more likely to be overweight or obese at the time of diagnosis. Obesity at the time of cancer diagnosis has been associated with poorer prognosis, and weight gain in combination with radiation and chemotherapy in survivors appears to accelerate obesity-associated chronic disease.10 Therefore, weight management is a priority for cancer survivors.11 The paradigm shift in the cancer care treatment community from disease-focused to wellness-comprehensive care affords a unique opportunity for healthcare providers to promote healthy lifestyle behaviors for cancer survivors.11,12 Physical activity is a modifiable lifestyle behavior positively associated with weight management and numerous physiologic effects and psychological health outcomes such as cardiorespiratory fitness, fatigue, and quality of life.13–17 In addition, several reviews and meta-analyses have demonstrated that physical activity is associated with a lower risk of death, all-cause mortality, and cancer recurrence, particularly among breast and colorectal cancer survivors.18–20 Physical activity also reduces other comorbid chronic diseases such as type 2 diabetes and cardiovascular disease.11,21 Despite this evidence, it is estimated that <10% of cancer survivors will be active during treatments and only 20%–30% will be active after treatments.22,23 This suggests healthcare providers should develop a working knowledge of the role of physical activity in cancer survivorship (Figure 1) to help patients adopt and maintain a physically active lifestyle.24–26 This review aims to summarize the current physical activity recommendations and the evidence linking physical activity to improvements in weight management, physiological effects, and psychological health outcomes for cancer survivors. Figure 1 Physical activity and cancer control framework. From Courneya KS, Friedenreich CM. Physical activity and cancer control. Semin Oncol Nurs. 2007;23(4):242–252. Copyright 2007. Reprinted with permission from Elsevier.