Implications for breast cancer survival
The study confirmed previous reports that alcohol consumption, post-menopausal obesity and, to a lesser extent, cigarette smoking, are associated with increased risk of estrogen receptor positive (ER+) breast cancer. The synergistic effect of smoking with alcohol consumption is a new finding. The question for many breast cancer survivors is whether reducing or eliminating smoking and alcohol consumption and achieving normal weight would result in a meaningful reduction in risk of a new primary breast tumor.
The available evidence indicates that weight gain during and after breast cancer treatment reduces survival, but we are not aware of any studies that have examined the impact of weight loss in overweight survivors (i.e., weight loss not associated with illness). Nor has the effect on risk of recurrence of abstaining from alcohol or quitting smoking been studied. It makes sense that breast tissue with demonstrated susceptibility to the development of breast cancer would be vulnerable to generating new breast tumors over time. Following this logic, if factors that contributed to the tendency to develop cancer are removed, the risk of recurrence might be reduced.
For women who are not able to stop smoking or drinking, there is evidence that increased consumption of fruits and vegetables can counteract some of the heightened risk of recurrence associated with cigarettes and alcohol. We suggest consuming a wide variety of fruits and vegetables from our recommended food list. Obesity influences the risk of post-menopausal breast cancer through several mechanisms, among which is that it increases circulating estrogen. Treatment with tamoxifen or other anti-estrogen agents can potentially reduce this aspect of the increased risk of ER+ breast cancer associated with being overweight for postmenopausal women.