Body Mass Index (BMI) is not a cancer risk factor for BRCA1/2 carriers: a Systematic Review and Meta-analysis of case-control studies
Abstract Background Breast cancer susceptibility gene 1 and 2 (BRCA 1/2) pathogenic germline variants (gPV) are involved in an increased cumulative risk for cancers (above all breast and ovarian cancers). Overweight/obesity is a well-known systemic condition conferring higher cancer risk too. Methods We performed a systematic review collecting data on Medline, Scopus, and Cochrane-Library database until August 2020. We included four case-control studies (Fu et al, Bissonauth et al, Khachatryan et al, Nkondjoc et al) assessing the risk for cancer according to different BMI strata in BRCA-positive healthy individuals. Results Four studies for a total of 1148 patients evaluated breast and ovarian cancer risk in a healthy BRCA1/2 population. No other tumor histotypes risk has been observed within the selected population. Pooled results demonstrated that different BMI conditions (lower or upper 25 kg/m2) were not associated with increased cancer risk (OR 1.15, 95% CI 0.92–1.44 and OR 1.48, 95% CI 0.84–2.62 respectively). Additionally, no differences were reported according to menopausal status. Conclusion Despite the need for other prospective investigations in larger cohorts, our results suggest no BMI contribution in cancer risk in this special population, determining a new important point of view and a new potential field of investigation.