Supplementary Material for: Unexpected Twin Pregnancy in a BRCA2-Positive Breast Cancer Patient with Post-Chemotherapy Amenorrhea: A Case Report and Call for Comprehensive Contraceptive Counseling

Background: Contraceptive counseling for cancer patients, especially during periods of treatment-induced amenorrhea, is often overlooked. This can lead to unexpected pregnancies with significant implications for patient care and outcomes.

Case Presentation: We report a case of a 38-year-old BRCA2-positive breast cancer patient who experienced an unexpected twin pregnancy while undergoing treatment with tamoxifen and olaparib. The patient had been amenorrheic since initiating chemotherapy for more than 600 days and had not received contraceptive counseling. The pregnancy was discovered during routine follow-up imaging computed tomography. After thorough counseling regarding the teratogenic potential of her treatments and radiation exposure, and considering the patient's strong desire to prioritize her own treatment to safeguard her existing three children, the pregnancy was terminated.

Conclusion: This case highlights the need for comprehensive contraceptive counseling throughout cancer treatment, regardless of apparent fertility status. It also emphasizes the importance of considering both teratogenicity of treatments and patients' personal circumstances in managing unexpected pregnancies in cancer patients.

Keywords: Breast Neoplasms; BRCA2 Protein; Contraception; Amenorrhea; Pregnancy, Unplanned