SUMMARY
Introduction: Breast cancer is one of the most common malignancies in women and is relatively rare in men (12% vs. 0.1%). The effect of sex hormones on the risk and development of cancer among transgender people is not fully understood, although it is well known that steroid hormones affect changes in breast tissue, e.g., the deposition of breast fat and the formation of lobules and ducts in transgender women and the growth of thefibrous tissue.Matherials and methods: This paper reviews the recent literature (available on PubMed, NIH, Google Scholar, and Science Direct) from 2012 to May 2022 on the incidence of breast cancer in the transgender population. Seventeen case reports of breast cancer among transgender men were described (median age: 42; mean number of years of drug use: 7; most commonly diagnosed cancer type: invasive ductal carcinoma; most expressed receptors: estrogen and progesterone) and 15 cases in transgender women (median age: 53; average number of years of drug use: 16; most commonly diagnosed cancer type: invasive ductal carcinoma; most expressed receptors: estrogen and progesterone).Results: The discussed cases indicate a longer hormone therapy in transgender women without a cancer diagnosis and a later age of diagnosis compared to transgender men. Both transgender men and transgender women had a lower median age of cancer diagnosis compared to cisgender women and men.