Accumulating evidence suggests that lifestyle behaviors such as physical activity and dietary patterns may impact breast cancer prognosis. Observational data suggest that patients who are overweight and inactive have higher rates of breast cancer recurrence and overall mortality as compared to patients who are leaner and more active.1-4 Interventional studies in breast cancer survivors have demonstrated that changes in diet and physical activity patterns are feasible and are associated with improvements in quality of life, less treatment-related weight gain, and fewer disease- and treatment-related side effects.5 Some preliminary evidence suggests that lifestyle change may also improve prognosis in breast cancer,6 but much work still needs to be done to validate this and determine which types of lifestyle change are most important. This chapter provides an overview of the observational and interventional work in this area, as well as clinical recommendations for breast cancer survivors.
Four recent prospective observational studies have demonstrated that women who are physically active after breast cancer diagnosis have a better prognosis than sedentary women (Table 105-1). The Nurses' Health Study investigators looked at the relationship between physical activity and rates of breast cancer recurrence and death in a cohort of 2987 women diagnosed with stage I-IIIa breast cancer and demonstrated that patients who engaged in more than 9 metabolic equivalent task (MET) hours/week of physical activity, equivalent to walking at an average pace for 3 h/wk, had a 50% lower risk of breast cancer recurrence, breast cancer death, and all-cause mortality than women who were inactive.3 The decreased risk of recurrence and death associated with exercise was seen in both pre- and postmenopausal patients and was independent of body mass index (BMI). Similar results were seen the Collaborative Women's Longevity Study, which collected information regarding physical activity behaviors from 4482 women who had been diagnosed with early-stage breast cancer at least 5 years previously.4 Women expending more than 2.8 MET h/wk had lower breast cancer mortality when compared to women with lower levels of activity (hazard ratio [HR] 0.65, 95% CI 0.39-1.08 for 2.8-7.9 MET h/wk; and HR 0.59, 95% CI 0.35-1.01 for 8.0-20.9 MET h/wk). Results were again independent of patient age or BMI.
Table 105-1 Prospective Observational Studies of Physical Activity after Diagnosis and Breast Cancer Outcome ||Download (.pdf)
Table 105-1 Prospective Observational Studies of Physical Activity after Diagnosis and Breast Cancer Outcome
|Study||N||Menopausal Status||Median Follow-Up (mo)||Timing of Exercise Assessment||Results|
|Nurses' Health Study (NHS)3||2987||Pre and Post||96||At least 2 years post-diagnosis||At least 9 MET h/wk had significant reduction in recurrence, breast cancer death, and overall death: HR 0.57 (0.38-0.85)|
|Women's Healthy Eating and Living Study (WHEL)8||1490||Pre and Post||80||At study enrollment (within 4 years of diagnosis)||Patients who consumed ≥ 5 vegetable/fruit servings/d plus 9 MET h/wk of activity had significant reduction in mortality: HR 0.56 (0.31-0.98)...|