Trends in fertility preservation treatments in Japan until 2023: analysis of the Japan Oncofertility Registry.

Background: Fertility preservation for patients with cancer or other diseases who receive gonadotoxic treatment has gained importance as cancer survival rates increase. In Japan, a database for registering all fertility preservation patients, named the Japan Oncofertility Registry (JOFR), was established in 2018. This study aimed to analyze recent trends in fertility preservation in Japan utilizing data from the JOFR.

Methods: Data was extracted from the JOFR for patients who consulted fertility preservation teams until May 2024. A descriptive analysis was conducted to examine trends in patient demographics, cancer types, fertility preservation treatments, complications, and outcomes. The data covered the period from diagnosis to fertility preservation and subsequent usage or disposal of frozen specimens.

Results: A total of 11,510 patients were recorded, with 9491 undergoing fertility preservation treatments. The number of patients increased steadily after 2006. After 2021, the number of female patients was much higher than the number of male patients. The most common primary diseases were breast cancer among women and testicular tumors and leukemia among men. There were some complications including ovarian hyperstimulation syndrome (5.0%), bleeding (0.12%), and infections (0.05%) for women. Seven hundred and sixty clinical pregnancies were recorded, with 440 using preserved specimens. The discard rate was 16.3% for men and 3.7% for women.

Conclusion: The study highlights recent trends in the growing number of cases undergoing fertility preservation in Japan. It also identifies several issues to be solved in fertility preservation in Japan, regarding its efficacy and safety, as well as the medical provision system.