Epidemiology

Cancer

Internal medicine

Oncology

Serous fluid

Carcinoma

Serous carcinoma

Clear cell

Ovarian cancer

Clear cell carcinoma

Medicine

Cohort

Gastroenterology

Gynecologic Oncology

Objective To examine the trends of epithelial ovarian cancer histologic subtypes in Japan. Methods A nationwide retrospective registry study was performed between 2002 and 2015 (Japan cohort, n = 48,640). Trends were also examined in The Surveillance, Epidemiology, and End Results Program (US cohort, n = 49,936). Time-specific proportional changes of four major histological subtypes (serous, clear cell, endometrioid, and mucinous) were examined. Results The Japan cohort had more stage I disease (44.1% versus 24.9%) and less stage IV disease (10.0% versus 23.1%) than the US cohort (P < 0.001). The Japan cohort had more non-serous histology, particularly clear cell carcinoma (26.9% versus 8.4%), than the US cohort (P < 0.001). In the Japan cohort, proportion of clear cell carcinoma increased significantly from 23.4% to 29.1% between 2002 and 2010 (P < 0.001). Among stage I disease, clear cell carcinoma increased significantly in the Japan cohort from 32.9% to 40.3% between 2002 and 2015 (P < 0.001), whereas mucinous carcinoma increased significantly in the US cohort from 15.0% to 24.8% (P = 0.01). In 2015, clear cell carcinoma was most common among women aged <50 years from the Japan cohort (30.2%) versus serous carcinoma in the US cohort (50.8%). In the Japan cohort, the peak age was 75 years for serous, 57 for clear cell, and 45 for endometrioid carcinoma (P < 0.001). Mucinous carcinoma decreased until 43 years and increased again after age 73 years (P < 0.001). Conclusion Characteristics of epithelial ovarian cancer in Japan are largely different compared to the US. In Japan, clear cell carcinoma has increased significantly in recent years to account for nearly 30% of epithelial ovarian cancer.

Trends and characteristics of epithelial ovarian cancer in Japan between 2002 and 2015: A JSGO–JSOG joint study