Case Report

Interdisciplinary Management of Transgender Individuals at Risk for Breast Cancer: Case Reports and Review of the Literature

The umbrella term of “transgender” includes people who experience their gender identity as opposite to the gender assigned to them at birth and may include people who are nonbinary (not exclusively masculine or feminine). For gender transition, current standard of care regimens can include gender-affirming hormonal treatment (GAHT) and/or surgery. After the pioneering work of the endocrinologist, Dr Harry Benjamin, transgender individuals have been receiving GAHT since the early 1960s.¹ Trans women are assigned to the male gender at birth, but identify with the female gender (male-to-female). To acquire and maintain feminization they undergo estrogen therapy.²

Assigned female at birth, trans men identify as male (female-to-male). They frequently pursue testosterone therapy to induce masculinization.

There are almost 1 million transgender adults in the United States and the proportion has increased from 0.2% in 2007 to 1.8% in 2016.³ A 2018 study by the Center of Expertise on Gender Dysphoria in the Netherlands also reported increased referrals to their clinic since 1972. For trans women, this number increased from 14.9 per year between 1972 and 1979 to 185.2 per year between 2010 and 2014. Similarly, the annual referral rate for trans men increased from 3.8 cases (1972-1979) to 103.6 cases (2010-2014).⁴ As the number of transgender individuals increases, there is a growing need to understand the cancer risk in this population.

Breast cancer is the most frequently diagnosed cancer in women in the United States with 126 new cases per 100,000 women each year.⁵ Male breast cancer only represents 1% of all breast cancer cases and <1% of cancers in men.⁶ Certain predisposing risk factors are implicated in male and female breast carcinogenesis. Mutations in tumor suppressor genes BRCA1, DNA repair associated (BRCA1) and BRCA2, DNA repair associated (BRCA2) are 2 genetic aberrations that predispose an individual to breast cancer. They account for 5% to 10% of female and 5% to 20% of male breast cancer cases.⁷ The frequency of breast cancer in transgender individuals, as well as the effect of GAHT on the risk of breast cancer, remains largely unexplored.

In this report, we present 2 cases: (1) a 32-year-old trans woman with a family history of breast cancer and a germline BRCA2 mutation; and (2) a 29-year-old trans man with a strong family history of breast cancer who was incidentally diagnosed with ductal carcinoma in situ (DCIS) at the time of chest reconstruction surgery. We discuss these cases from a multidisciplinary perspective thereby summarizing the current knowledge about breast cancer in transgender individuals and reviewing the inherent risk of breast cancer while undergoing GAHT.

We performed a systematic literature search in the PubMed database between 1968 and 2018 and identified 2 population-based observational studies that reported the incidence of breast cancer in 3102 and 5135 transgender individuals.8, 9 Twenty cases of breast cancer in trans women and 16 cases in trans men have been reported (Table 1).8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26 We also included a recent observational study on 3891 transgender individuals on the basis of its preliminary data published in early 2018.²⁷