Aim: To describe real-world breast cancer medications among reproductive-age women. Patients & methods: Using data from a Japanese claims database, anticancer prescriptions were classified into seven categories of amenorrhea risk based on fertility preservation guidelines. Results: We identified 2999 women with records of breast cancer and anticancer prescription from 2005 to 2018. The proportions of prescriptions were as follows: high, 4.1-12.9%; intermediate: 6.0-16.3%; low: 0.4-2.3%; very low/no: 0.3-12.2%; unknown: 33.9-45.5%; unlisted combination: 12.2-23.4%; and unlisted drug: 12.5-26.7%. The common drugs in the unknown category were trastuzumab (n = 1527), docetaxel (n = 1014), and paclitaxel (n = 995). For medications unlisted in the guidelines, various drugs and drug combinations were observed. Conclusion: Numerous anticancer drugs are currently being prescribed with insufficient evidence regarding amenorrhea risk.
Keywords: breast cancer; chemotherapy; claims database; guideline; infertility; oncofertility.
Lay abstract The ability to have children for breast cancer patients is one of the key issues of cancer survivorship, especially because recent progress in anticancer treatments has enabled patients to achieve longer survival. The fertility preservation guidelines of the American Society of Clinical Oncology (2006) introduce some anticancer treatments that carry potential risks to future fertility. In this study, the anticancer prescriptions of 2999 patients with breast cancer aged between 15 and 49 years were examined. Results showed that several medications are prescribed despite the lack of information on the risk of infertility. This suggests that further research is required to fill the evidence gap, and that decision aid through adequate counseling should be undertaken.