The effect of overweight and nutrition on prognosis in breast cancer.

BACKGROUND

Breast cancer is the most common cancer in women. Body weight and nutrition are known to play an important role in its pathogenesis. The question thus arises whether lifestyle factors might influence the prognosis of breast cancer, potentially offering new approaches for secondary prevention.

METHODS

We selectively searched the Medline database for all studies and meta-analyses on this topic that were published from 1966 to June 2010. We evaluated the cohort studies, interventional trials, and meta-analyses with respect to three target variables: tumor recurrence, tumor-specific mortality, and overall mortality.

RESULTS

A high body-mass index (BMI) at the time of diagnosis of breast cancer is associated with higher overall mortality, as is weight gain at later times. A low-fat diet rich in fruit, vegetables, and fiber seems to be weakly associated with a better prognosis. On other hand, there is no evidence for any benefit from micronutrients, supplements, or antioxidant foods. Alcohol consumption does not affect the outcome in breast cancer. Two intervention trials of reduced fat intake showed no effect on survival, but the target of the intervention was not met in either trial.

CONCLUSION

The intervention trials yielded negative results. Nevertheless, in view of the methodological difficulties in this area of research and the overall life situation of women with breast cancer, the authors recommend a health-promoting lifestyle with avoidance of overweight and a low-fat diet rich in fruit, vegetables, and fiber.