SUN-LB8 Cross Sex Hormone Therapy and Breast Cancer in Transgender Male to Female

Case Presentation: We are presenting a 53-year-old Male to Female transgender patient who has been receiving estradiol valerate injections every 14 days for 13 years and had no gender surgical reassignment procedures or breast implants. Her past medical history was significant for HIV on Highly Active Anti-retroviral therapy (HAART). No family history of breast cancer. She presented with severe bilateral left elbow, lower back and bilateral chest pain for 3 days. Chest CT done to exclude pulmonary embolism showed an incidental 4 cm right breast mass. Enlarged lymph nodes in the right axilla, scattered lytic lesions in the axial skeleton and the left humeral head were also noted. Breast exam was not performed until the significant findings were seen in CT chest and it showed a palpable hard-circumscribed subareolar right breast mass without skin changes. Ultrasound guided biopsy of the breast mass confirmed invasive ductal carcinoma of the breast. The patient had no previous mammogram testing. Oncology work-up was positive for estrogen and progesterone receptors but negative for human epidermal growth factor-2 receptor. The patient opted to return home in another state to seek treatment and further oncological workup but subsequently lost follow up. Discussion: Male to female breast cancer was first recognized in 1968. However, risk factors for this condition remain unclear. In our patient, long-term use of Cross-sex Hormone Therapy (CHT) represented a major risk factor for breast cancer. In a Dutch study, the risk of breast cancer increased during a relatively short duration of CHT and the cancer characteristics reassembled female pattern. As theoretically implicated, increased estrogen exposure in males may have a role in the proliferation of neoplastic breast epithelium. There are growing evidence to support increasing rates of breast cancer in HIV-positive population, making it a potential risk factor as well. Loss of CXCR-4 protective effect promoted by HIV virus may explain the increase in the breast cancer incidence after the introduction of HAART. In general, routine screening for breast cancer in MTF transgender population remains controversial. The Endocrine Society Clinical Practice guidelines suggest that MTF transsexual individuals who have no known increased risk of breast cancer should follow screening guidelines for biological women. While the Canadian Cancer Society recommends screening mammography every two years for MTF individuals taking CHT for more than 5 years and those between the ages of 50 and 69 years. Conclusion:Breast cancer in MTF transgender patients is associated with receiving CHT and represents diagnostic and treatment challenge. More research is need to comment on routine breast cancer screening in this population. However, physicians should remember performing a regular breast exam in MTF individuals looking for a possible mass.