Patients who had a breast cancer diagnosis (including those with ductal carcinoma in situ (DCIS)), who were age ≥18 years at the time of diagnosis and identify as a gender and/or sex that is different from their sex assigned at birth (e.g., transgender, nonbinary, genderqueer, etc.) between 1/1/1990 - 7/1/2023.

Describe the method of breast cancer diagnosis (self detected vs screen detected vs healthcare provider detected) and compare to the published data from cisgender women by determining means and standard deviation and comparing rates using the Wilcoxon signed-rank test.

Assess breast cancer risk factors (family history, genetics, etc.), including a prior use of gender-affirming hormone therapy and/or gender-affirming surgery on tumor receptor status and stage at diagnosis using t-test and chi-squared test.

Report breast cancer management strategies (type of breast surgery, receipt of radiation, etc.) through descriptive and comparative staststics with a focus on the use of adjuvant endocrine therapy and gender-affirming hormone therapy for patients with hormone-receptor positive disease using t-test and chi-squared test.

Breast cancer local and distant recurrence, overall survival, and disease-free survival using Kaplan-Meier analysis. Cox Proportional Hazards model will be used to estimate the effect of various factors on distant metastasis-free and overall survival.