The DAMA trial: a diet and physical activity intervention trial to reduce mammographic breast density in postmenopausal women in Tuscany, Italy. Study protocol and baseline characteristics.

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Aims and background. High mammographic breast density (MBD) is an established risk factor for breast cancer (BC). The influence of diet and physical activity (PA) on MBD has long been investigated. In an observational study of a cohort in Florence, we observed inverse associations between consumption of vegetables and olive oil and moderate leisure-time PA and MBD, while high alcohol intake and high glycemic load diets were positively associated with MBD. We set out to investigate whether dietary and PA interventions were able to reduce MBD in postmenopausal women with high MBD (>50%). Methods and study design. The DAMA (Diet, physical Activity and MAmmography) trial, a factorial randomized trial involving healthy nonsmoking postmenopausal women not using hormone replacement therapy and having MBD >50%, is aimed at evaluating the ability of a 24-month intervention based on moderate-intensity PA and/or dietary modification focused on plant foods with a low glycemic load, low in saturated fats and alcohol, and rich in antioxidants and fiber, to reduce the percent MBD. Participants have been randomized to 1 of 4 study arms (diet, PA, diet + PA, control). Dietary and PA habits and anthropometry are collected at baseline and at the end of the intervention phase together with repeated blood and urine samples. The primary outcome of the study is the absolute change in percent MBD as assessed on baseline and follow-up digital mammograms performed in the framework of the local screening program. Results. Of 728 eligible women, 234 (32.1%) agreed to participate. We did not observe any difference across study arms in the baseline distribution of variables of interest related to diet and lifestyle. Conclusions. The DAMA trial may contribute to a better understanding of MBD determinants. This will provide insight into the pathogenesis of BC and may allow the development of strategies for primary prevention focused on high-MBD groups that are easily identifiable in large-scale BC screening programs.

TRIAL REGISTRATION NUMBER

ISRCTN28492718.