Statistics of Visceral Sarcoma in Japan: Report From the Population-Based National Cancer Registry (NCR) in Japan

Background and objectives: Sarcomas developing in the visceral organs are extremely rare, with no previous reports to describe their national epidemiology. We analyzed Japanese domestic statistics for visceral sarcoma, using the National Cancer Registry (NCR) in Japan, a population-based database launched in 2016. Methods: We identified 3245 cases of visceral sarcomas in the NCR dated 2016-2019 to analyze demographic and disease information, initial diagnostic process, volume and type of the hospitals, treatment, and prognosis. Results: Visceral sarcoma shows a higher prevalence in the older generation (60+ years), with a significant male predominance (p = 0.006). Leiomyosarcomas occurred frequently in the gastrointestinal tract (N = 240; 39.5%), and angiosarcomas in the liver, gall bladder, pancreas, and spleen (N = 244; 43.9%). Visceral sarcomas were often treated in facilities of lower volume without specific adjuvant treatments (p < 0.001). The cumulative 3-year overall survival was 44.8%, and several factors such as surgery or absence of chemotherapy positively affected survival. Conclusions: This is the first nationwide study in Japan to analyze the inclusive epidemiology of visceral sarcomas. Visceral sarcomas are characterized by senior and male predominance with relatively poor prognosis, often managed in nonspecialized facilities and rarely with adjuvant therapies. Several histologic subtypes had the propensity to develop in specific organs.