Breast cancer in transgender patients: A systematic review. Part 2: Female to Male.

Transgender men or Female-to-Male (FtM) patients' risk of breast cancer and screening recommendations remain unclear. The objective of this study is to perform a systematic review of the literature and document all reported cases of FtM breast cancer as well as provide research recommendations. Following PRISMA guidelines, MEDLINE, ProQuest, PubMed, and Cochrane Database of Systematic Reviews were searched from inception until September 15, 2016. Screening and data extraction were performed in duplicate by two independent reviewers (RH and JS). Study quality was assessed using a component-based system. Study characteristics, patient demographics, breast cancer characteristics, presentation and management are reported. Eight articles met inclusion criteria representing 17 transgender men with breast cancer. Median age at diagnosis was 44.5 years. Breast cancer types included: 8 invasive ductal carcinomas, two tubular carcinomas and seven unrecorded. Twelve of the 14 known hormone status tumours were estrogen receptor positive (85.7%), of which nine were also progesterone positive. The most common was breast lump (n = 6) and four patients had local regional or distant disease at presentation. Management was reported for ten patients: six patients underwent mastectomy (60.0%), three radiation (30.0%), and five chemotherapy (50.0%). Breast cancer is present in transgender men and the risk is dependent on top surgery; those with top surgery appear to be lower risk than natal females. More longitudinal studies and better population data are required to contribute to evidence-based screening recommendations. Crown