Abstract
BACKGROUND: Different histologic subtypes of ovarian cancer have distinct risk factors, clinical features, and prognosis. This analysis intends to examine the regional differences in the incidence rates of different histologic subtypes of ovarian cancer in China and the changes in incidence in different age groups. METHODS: Data on ovarian cancer in China from the Cancer Incidence in Five Continents, Volume XII database between 2013 and 2017 were employed in this descriptive study. The age-standardized incidence rates (ASR) of ovarian cancer for serous carcinoma (SC), mucinous carcinoma (MC), endometrioid carcinoma (EC), clear cell carcinoma (CCC), and other unidentified subtypes were calculated. The crude incidence rates of ovarian cancer in different age groups were calculated. Regional differences were analyzed using the six major administrative regions (Northeast, North China, Northwest, East China, Central South, and Southwest) and 20 provincial administrative regions, respectively. RESULTS: A total of 32,817 ovarian cancer patients were included, among which 7,742 (23.59%) had SC, 1,709 (5.21%) had MC, 1,319 (4.02%) had CCC, 1,233 (3.76%) had EC, and 20,814 (64.42%) had unclassified histologic subtypes. The ASR was 5.31 (95%CI: 5.26-5.37) per 100,000 people for overall ovarian cancer, 1.27 (95%CI: 1.24-1.29) for SC, 0.30 (95%CI: 0.28-0.31) for MC, 0.21 (95%CI: 0.20-0.22) for EC, 0.22 (95%CI: 0.21-0.23) for CCC, and 0.47 (95%CI: 0.47-0.48) for unclassified subtypes. There were differences in the distribution of subtypes in different regions of China: SC and CCC occurred most in the Northeast and North China, MC in the Northeast and Central South, and EC in the North China and Central South. The distribution of subtypes also varied across economic level regions, with higher frequencies of SC, CCC, and EC in the high economic level group. Furthermore, the crude incidence rates of SC subtypes in China increased with age, but showed a decreasing trend at age 60 years. The crude incidence rates of CCC, EC, MC, and other subtypes do not change distinctly with age. CONCLUSION: This study explored the incidence distribution of histologic subtypes of ovarian cancer in China, which may provide a reference for the screening, prevention, and control of the disease in the Chinese population.