Characteristics of Gender-Diverse Patients With Breast Cancer

Importance: Limited granular data exist on breast cancer in transgender, nonbinary, and/or gender-diverse (TGD) individuals. Objective: To describe patient demographic and tumor clinicopathological variables, clinically relevant risk factors, method of breast cancer detection, treatment characteristics, and locoregional outcomes and to estimate a 5-year breast cancer-specific survival (BCSS). Design, Setting, and Participants: This cohort study obtained data on patients treated from 1990 to 2023 from 22 US academic medical centers using institutional databases, electronic medical records, and tumor registries. Included participants were TGD individuals 18 years or older with stage 0 to IV breast cancer. A comparative breast cancer cohort was selected from the 2016 to 2021 Surveillance, Epidemiology, and End Results Program (SEER) breast cancer dataset. Data were analyzed from January to October 2025. Exposure: Breast cancer. Main Outcomes and Measures: Estimated 5-year BCSS and locoregional recurrence rates. Wilcoxon rank sum and χ2 tests were used to compare continuous and categorical variables. Kaplan-Meier analysis was used to estimate 5-year BCSS. Results: A total of 112 TGD persons (median [IQR] age at diagnosis, 42.5 [36.5-51.0] years; 104 individuals [92.9%] were assigned female at birth) with breast cancer and 1 with bilateral disease were included in the analysis. Forty-three patients (38.4%) used gender-affirming hormone therapy before diagnosis. Among the entire cohort, 58 patients (51.8%) detected their own breast cancer, 68 (60.7%) had a familial breast cancer history, and 16 (14.3%) had a pathogenic germline variant. Tumors were predominantly hormone receptor positive (96 [85.7%]) and early stage (29 [25.7%] ductal carcinoma in situ [DCIS]; 51 [45.1%] stage I). The TGD cohort, compared with patients with breast cancer in the SEER dataset (N = 480 915), was younger (median [IQR] age, 42.5 [36.5-51.0] years vs 62.0 [52.0-72.0] years), had a higher proportion of persons assigned male at birth (8 [7.1%] vs 3522 [0.7%]), more often had progesterone receptor-positive disease (89 [79.5%] vs 335 491 [69.8%]), and presented with earlier-stage disease (eg, DCIS: 29 [25.9%] vs 79 604 [16.6%]). With a median (IQR) follow-up time for the TGD cohort of 38 (24-74) months, 5-year BCSS was favorable at 96.2% (95% CI, 85.3%-99.0%). Conclusions and Relevance: This cohort study of TGD patients with breast cancer found that this population was young and often detected their own tumors via self-examination, suggesting opportunities to improve early detection through screening for individuals at elevated risk. Although short-term BCSS appeared favorable, prospective research is essential to define evidence-based guidelines and elucidate long-term outcomes.