Trend and characteristics of minimally invasive surgery for patients with endometrial cancer in Japan

Objective: Owing to the potential benefits of minimally invasive hysterectomy for endometrial cancer, the practice pattern has recently shifted in Japan. This study examined the trends in minimally invasive surgery (MIS) in patients with endometrial cancer in Japan. Methods: This retrospective observational study examined the Japan Society of Obstetrics and Gynecology Tumor Registry database between 2015–2019. This study examined the timespecific proportion change and predictors of MIS use in initial endometrial cancer treatment in Japan, and compared it with the use of abdominal surgery. Additionally, the association between hospital surgical treatment volume and MIS use was examined. Results: A total of 14,059 patients (26.5%) underwent minimally invasive hysterectomy, and 39,070 patients (73.5%) underwent abdominal hysterectomy in the study period. Patients who underwent MIS were more likely to be treated at high-volume centers, younger, central, or western Japan residents, registered in recent years, and had a tumor with stage I disease, type 1 histology, and less myometrial invasion (all adjusted p<0.05). The proportion of MIS treatments increased from 19.1% in 2015 to 34.3% in 2019 (p<0.001). On multivariable analysis, treatment at high-volume centers was a contributing factor for MIS (adjusted odds ratio=3.85; 95% confidence interval=3.44–4.30). MIS at high-volume centers increased significantly from 24.8% to 41.0% (p<0.001) during the study period, whereas MIS at lowvolume centers remained at median 8.8%. Conclusion: MIS has increased significantly in recent years, accounting for nearly 34% of surgical management of endometrial cancer in Japan. High-volume treatment centers take the lead in performing MIS.