Real-world anticancer medications for reproductive-age women with breast cancer by using a claims database in Japan.

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.