Brigid M. Lynch

State of the epidemiological evidence on physical activity and cancer prevention

BACKGROUND Physical activity is a modifiable lifestyle risk factor that has the potential to reduce the risk of most major cancer sites. METHODS We examined the strength, consistency, dose-response and biological plausibility of an association between physical activity and risk of colon, breast, endometrium, lung, prostate, ovarian, gastric, rectal, pancreatic, bladder, testicular, kidney and haematological cancers. We also estimated the population-attributable risk (PAR) for physical inactivity and cancer in 15 European countries. RESULTS There is convincing or probable evidence for a beneficial effect of physical activity on the risk of colon, breast and endometrial cancers. The evidence is weaker for ovarian, lung and prostate cancers and generally either null or insufficient for all remaining cancers. Several hypothesised biological mechanisms include a likely effect of physical activity on insulin resistance, body composition, sex steroid hormones and a possible effect on vitamin D, adipokines, inflammation and immune function. Somewhere between 165,000 and 330,000 cases of the six major cancers (breast, colon, lung, prostate, endometrium and ovarian) could have been prevented in 2008 in Europe alone if the population had maintained sufficient levels of physical activity. CONCLUSION There is strong and consistent evidence that physical activity reduces the risk of several of the major cancer sites, and that between 9% and 19% of cancer cases could be attributed to lack of sufficient physical activity in Europe. Public health recommendations for physical activity and cancer prevention generally suggest 30-60 min of moderate or vigorous-intensity activity done at least 5d per week.

Sedentary Behavior and Cancer: A Systematic Review of the Literature and Proposed Biological Mechanisms

Background: Sedentary behavior (prolonged sitting or reclining characterized by low energy expenditure) is associated with adverse cardiometabolic profiles and premature cardiovascular mortality. Less is known for cancer risk. The purpose of this review is to evaluate the research on sedentary behavior and cancer, to summarize possible biological pathways that may underlie these associations, and to propose an agenda for future research. Methods: Articles pertaining to sedentary behavior and (a) cancer outcomes and (b) mechanisms that may underlie the associations between sedentary behavior and cancer were retrieved using Ovid and Web of Science databases. Results: The literature review identified 18 articles pertaining to sedentary behavior and cancer risk, or to sedentary behavior and health outcomes in cancer survivors. Ten of these studies found statistically significant, positive associations between sedentary behavior and cancer outcomes. Sedentary behavior was associated with increased colorectal, endometrial, ovarian, and prostate cancer risk; cancer mortality in women; and weight gain in colorectal cancer survivors. The review of the literature on sedentary behavior and biological pathways supported the hypothesized role of adiposity and metabolic dysfunction as mechanisms operant in the association between sedentary behavior and cancer. Conclusions: Sedentary behavior is ubiquitous in contemporary society; its role in relation to cancer risk should be a research priority. Improving conceptualization and measurement of sedentary behavior is necessary to enhance validity of future work. Impact: Reducing sedentary behavior may be a viable new cancer control strategy. Cancer Epidemiol Biomarkers Prev; 19(11); 2691–709. ©2010 AACR.

Physical Activity and Breast Cancer Prevention

Breast cancer is the most commonly diagnosed invasive malignancy and the second leading cause of cancer death in women. This chapter considers epidemiologic evidence regarding the association between physical activity and breast cancer risk from 73 studies conducted around the world. Across these studies there was a 25% average risk reduction amongst physically active women as compared to the least active women. The associations were strongest for recreational activity, for activity sustained over the lifetime or done after menopause, and for activity that is of moderate to vigorous intensity and performed regularly. There is also some evidence for a stronger effect of physical activity amongst postmenopausal women, women who are normal weight, have no family history of breast cancer, and are parous. It is likely that physical activity is associated with decreased breast cancer risk via multiple interrelated biologic pathways that may involve adiposity, sex hormones, insulin resistance, adipokines, and chronic inflammation. Future research should include prospective observational epidemiologic studies relating proposed biomarkers to breast cancer risk and also randomized controlled trials to examine how physical activity influences the proposed biomarkers. Exercise trials will provide more clarity regarding the appropriate type, dose, and timing of activity that relate to breast cancer risk reduction.

Associations of objectively-assessed physical activity and sedentary time with depression: NHANES (2005–2006)

BACKGROUND Studies provide conflicting evidence for the protective effects of moderate-to-vigorous-intensity physical activity on depression. Recent evidence suggests that sedentary behaviors may also be associated with depression. PURPOSE To examine the associations of accelerometer-derived moderate-to-vigorous-intensity physical activity and sedentary time with depression among a population-based sample. METHODS Cross-sectional study using 2,862 adults from the 2005-2006 US National Health and Nutrition Examination Survey. ActiGraph accelerometers were used to derive both moderate-to-vigorous-intensity physical activity and sedentary time. RESULTS Depression occurred in 6.8% of the sample. For moderate-to-vigorous-intensity physical activity, compared with those in quartile 1 (least active), significantly lower odds of depression were observed for those participants in quartiles 2 (OR=0.55, 95% CI, 0.34 to 0.89), 3 (OR=0.49, 95% CI, 0.26 to 0.93), and 4 (most active) (OR=0.37, 95% CI, 0.20 to 0.70) (p for trend p<0.01). In overweight/obese participants only, those in quartile 4 (most sedentary) had significantly higher odds for depression than those in quartile 1 (least sedentary) [quartile 3 vs 1 (OR=1.94, 95% CI, 1.01 to 3.68) and 4 vs 1 (OR=3.09, 95% CI, 1.25 to 7.68)]. CONCLUSION The current study identified lower odds of depression were associated with increasing moderate-to-vigorous-intensity physical activity and decreasing sedentary time, at least within overweight/obese adults.

Describing and predicting psychological distress after colorectal cancer

Psychological distress in cancer survivors can be detrimental to treatment adherence and self‐care tasks and is associated with poor health behaviors and decreased overall quality of life. The prevalence, course, and predictors of psychological distress after the diagnosis of colorectal cancer are to date not well described.

Effects of a Telephone-Delivered Multiple Health Behavior Change Intervention (CanChange) on Health and Behavioral Outcomes in Survivors of Colorectal Cancer: A Randomized Controlled Trial

PURPOSE Colorectal cancer survivors are at risk for poor health outcomes because of unhealthy lifestyles, but few studies have developed translatable health behavior change interventions. This study aimed to determine the effects of a telephone-delivered multiple health behavior change intervention (CanChange) on health and behavioral outcomes among colorectal cancer survivors. METHODS In this two-group randomized controlled trial, 410 colorectal cancer survivors were randomly assigned to the health coaching intervention (11 theory-based telephone-delivered health coaching sessions delivered over 6 months focusing on physical activity, weight management, dietary habits, alcohol, and smoking) or usual care. Assessment of primary (ie, physical activity [Godin Leisure Time Index], health-related quality of life [HRQoL; Short Form-36], and cancer-related fatigue [Functional Assessment of Chronic Illness Therapy Fatigue Scale]) and secondary outcomes (ie, body mass index [kg/m(2)], diet and alcohol intake [Food Frequency Questionnaire], and smoking) were conducted at baseline and 6 and 12 months. RESULTS At 12 months, significant intervention effects were observed for moderate physical activity (28.5 minutes; P = .003), body mass index (-0.9 kg/m(2); P = .001), energy from total fat (-7.0%; P = .006), and energy from saturated fat (-2.8%; P = .016). A significant intervention effect was reported for vegetable intake (0.4 servings per day; P = .001) at 6 months. No significant group differences were found at 6 or 12 months for HRQoL, cancer-related fatigue, fruit, fiber, or alcohol intake, or smoking. CONCLUSION The CanChange intervention was effective for improving physical activity, dietary habits, and body mass index in colorectal cancer survivors. The intervention is translatable through existing telephone cancer support and information services in Australia and other countries.

Objectively assessed physical activity, sedentary time and waist circumference among prostate cancer survivors: Findings from the National Health and Nutrition Examination Survey (2003-2006)

Physical activity is well-established on the cancer survivorship research agenda, but prostate cancer survivors remain an understudied population. Additionally, the unique relationships between sedentary time and health outcomes have not yet been considered in this group. We examined the associations of accelerometer-assessed physical activity and sedentary time with waist circumference in 103 prostate cancer survivors from the National Health and Nutrition Examination Survey 2003-2004 and 2005-2006. Participants wore an Actigraph accelerometer for 7 days, and activity levels were summarised as moderate-to-vigorous intensity activity (accelerometer counts/minute ≥ 1952), light-intensity activity (counts/minute 100-1951) and sedentary time (counts/minute < 100). Moderate-to-vigorous intensity physical activity was inversely associated with waist circumference (β=-6.728, 95% CI: -12.267, -1.190, P= 0.020), equating to a top versus bottom quartile difference of 13.7 cm. No discernable relationship existed between light-intensity activity or sedentary time and adiposity. This is the first study to objectively measure the activity levels of prostate cancer survivors. Increasing moderate-to-vigorous activity may assist this population with weight management. More research into the relationships of light-intensity physical activity and sedentary behaviour with health outcomes among prostate cancer survivors is warranted, given the strong relationships seen in the broader population.

Associations of objectively assessed physical activity and sedentary time with health-related quality of life among colon cancer survivors

The primary purpose of this study was to determine associations of accelerometer‐assessed moderate‐ to vigorous‐intensity physical activity (MVPA) and sedentary time with health‐related quality of life (HRQoL) and physical function and well‐being in colon cancer survivors.

Associations of leisure-time physical activity with quality of life in a large, population-based sample of colorectal cancer survivors.

ObjectiveTo examine the associations between physical activity and quality of life for colorectal cancer survivors; and to describe the associations of medical and sociodemographic attributes with overall quality of life, and their moderating effects on the relationships between physical activity and quality of life.MethodsTelephone interviews were conducted with 1,996 colorectal cancer survivors recruited through the Queensland Cancer Registry. Data were collected on current quality of life; leisure-time physical activity pre- and post-diagnosis; cancer treatment and side-effects; and general sociodemographic attributes. Hierarchical generalized linear models identified variables significantly associated with quality of life.ResultsAfter controlling for sociodemographic variables, disease-specific variables, treatment side-effects, and pre-diagnosis leisure-time physical activity, there were significant differences in quality of life scores by post-diagnosis physical activity category. Compared to participants who were inactive after their diagnosis, those who were sufficiently active had a 17.0% higher total quality of life score. Physical activity also had a significant independent positive association with the physical well-being, functional well-being, and additional concerns subscales of the FACT-C.ConclusionsOur findings demonstrate that quite modest changes in leisure-time physical activity are associated with quality of life. Colorectal cancer survivors may benefit from a more active lifestyle.

Antecedents of domain‐specific quality of life after colorectal cancer

Objective: The present study prospectively assessed the influence of medical, socio‐demographic, psychological, and lifestyle variables on physical, social/family, emotional, functional well‐being and colorectal cancer‐specific concerns in a population‐based sample of colorectal cancer survivors.