Does hormone therapy counter the beneficial effects of physical activity on breast cancer risk in postmenopausal women?

Recreational physical activity and risk of triple negative breast cancer in the California Teachers Study

BACKGROUND

Evidence has accumulated showing that recreational physical activity reduces breast cancer risk. However, it is unclear whether risk reduction pertains to specific receptor-defined subtypes. Moreover, few studies have examined whether changes in the amount of recreational physical activity during adulthood influence breast cancer risk.

METHODS

A total of 108,907 women, ages 22 to 79 years with no history of breast cancer when joining the California Teachers Study in 1995-1996, completed a baseline questionnaire and were eligible for the study. Through 2012, 5882 women were diagnosed with invasive breast cancer. Breast cancer subtypes were defined by the expression status of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Multivariable Cox proportional hazards models provided adjusted hazard ratios (HRs) and 95 % confidence intervals (CIs) for breast cancer overall and ER/PR/HER2-defined subtypes associated with long-term (from high school through age 54 or age at cohort entry, whichever was younger) and baseline (during 3 years prior to baseline) recreational physical activity. Among women who also completed a follow-up questionnaire at 10 years after baseline in 2005-2008 (54,686 women, 1406 with invasive breast cancer), risk associated with changes in the amount of recreational physical activity from baseline to the 10-year follow-up (during 3 years prior to the 10-year follow-up) was determined.

RESULTS

Both long-term and baseline strenuous recreational physical activity were inversely associated with risk of invasive breast cancer (P trend ≤0.03). The observed associations were mainly confined to women with triple negative breast cancer (TNBC, ER-/PR-/HER2-, P trend ≤0.02) or luminal A-like subtype (ER+ or PR+ plus HER2-) who were former users of menopausal hormone therapy at baseline (P trend = 0.02, P homogeneity of trends ≤0.03). Moreover, women who consistently engaged in the highest level (≥3.51 h/wk/y) of strenuous recreational physical activity between baseline and 10-year follow-up had the lowest risk of breast cancer (HR = 0.71, 95 % CI = 0.52-0.98) when compared to those who were consistently low (≤0.50 h/wk/y).

CONCLUSIONS

Strenuous recreational physical activity is associated with lower breast cancer risk, especially TNBC. The benefit may be maximized by consistently engaging in high-intensity recreational physical activity during adulthood.

Feasibility of a lifestyle intervention for overweight/obese endometrial and breast cancer survivors using an interactive mobile application

OBJECTIVE

The study aimed to assess a one-month lifestyle intervention delivered via a web- and mobile-based weight-loss application (app) (LoseIt!) using a healthcare-provider interface.

METHODS

Early-stage overweight/obese (body mass index [BMI]≥25kg/m(2)) cancer survivors (CS) diagnosed in the past three years, and without recurrent disease were enrolled and received exercise and nutrition counseling using the LoseIt! app. Entry and exit quality of life (FACT-G) and Weight Efficacy Lifestyle Questionnaire (WEL) measuring self-efficacy were measured along with anthropometrics, daily food intake, and physical activity (PA) using the app.

RESULTS

Mean participant age was 58.4±10.3years (n=50). Significant reductions (p<0.0006) in anthropometrics were noted between pre- and post-intervention weight (105.0±21.8kg versus 98.6±22.5kg); BMI (34.9±8.7kg/m(2) versus 33.9±8.4kg/m(2)); and waist circumference (108.1±14.9cm versus 103.7±15.1cm). A significant improvement in pre- and post-intervention total WEL score was noted (99.38±41.8 versus 120.19±47.1, p=0.043). No significant differences were noted in FACT-G, macronutrient consumption, and PA patterns.

CONCLUSION

These results indicate that a lifestyle intervention delivered via a web- and mobile-based weight-loss app is a feasible option by which to elicit short-term reductions in weight. Though these results parallel the recent survivors of uterine cancer empowered by exercise and healthy diet (SUCCEED) trial, it is notable that they were achieved without encumbering significant cost and barrier-access issues (i.e. time, transportation, weather, parking, etc.).

Physical activity and cancer

Epidemiological evidence continues to accumulate on the benefits of physical activity in relation to cancer risk, progression and mortality. Recent studies suggest that sedentary behavior may independently affect cancer risk; they also focus on factors that may explain associations with physical activity, including cancer risk factors and whether associations exist for precancerous lesions. Despite enormous efforts to examine associations between physical activity and cancer, the literature is hindered by inconsistent assessment of physical activity across studies, and incomplete consideration of variation of effects across population subgroups (for example, defined by body size, age or sex) or tumors subgroups (organ location, receptor status, or molecular subtype), and whether other factors explain study results. Clearly, public health recommendations for appropriate changes in activity levels are needed; unfortunately, at this time, we have no exact physical activity prescription to give to the public.