Purpose: Breast cancer (BC) is the most frequent cancer among women in developed countries. Physical activity (PA), body mass index (BMI), and alcohol intake have been identified as relevant lifestyle modifiable risk factors for post-menopausal BC. We aimed to evaluate the role of these factors in modulating post-menopausal BC risk and to estimate the proportion of BC cases attributable to low PA, high BMI, and alcohol taking into account non-modifiable factors.
Methods: In the Italian section of the EPIC study, 15,010 post-menopausal women were recruited and provided information about dietary and lifestyle habits including PA, smoking, reproductive history, and anthropometric measurements. During 14.8 years of median follow-up, 672 incident BC cases (607 invasive and 65 in situ) were identified.
Results: In multivariate models, inverse associations with BC risk emerged for increasing level of total (p trend 0.02), leisure time (p trend 0.04), and occupational (p trend 0.007) PA. High BMI (HR 1.21; 95% CI 1.02-1.43 and HR 1.33; 95% CI 1.06-1.65 for overweight and obesity, respectively) and alcohol consumption higher than 10 g/day (HR 1.30; 95% CI 1.09-1.54) were associated with BC risk. We estimated that 30% (95% CI 8-50%) of post-menopausal BC cases would be avoided through an increase of leisure time PA, a BMI below 25.0, and consuming no more than one drink/day.
Conclusions: This large study carried out in Mediterranean women confirms the role of PA, BMI, and alcohol consumption in modulating post-menopausal BC risk and supports the potential benefits obtainable by modifying these lifestyle factors.
Keywords: Alcohol; Body mass index; Physical activity; Population attributable risk; Post-menopausal breast cancer; Prospective study.