Epidemiologic and Clinical Analysis of Cervical Cancer Using Data from the Population-Based Osaka Cancer Registry

Cervical cancer screening rate is extremely low and the governmental recommendation of HPV vaccine has been suspended for 5 years in Japan. Here, we utilized data from the Osaka Cancer Registry, collected between 1976 and 2012, to evaluate cervical cancer trends in Japan. Age-adjusted incidence, relative survival, and conditional survival rates were calculated using multiple imputation methods and period analyses in 25,826 cervical cancer cases. Association of survival rates and clinical factors, including patients' age, clinical stage, and treatment procedures, were also analyzed. A trend for significantly decreasing age-adjusted incidence of cervical cancer (per 100,000) began in 1976 but reversed after 2000, increasing significantly to date (annual percent change 1/4 3.8, 95% confidence interval, 2.7-4.8; age-adjusted rate: 28.0 in 1976, 9.1 in 2000, 14.1 in 2012). The 10-year relative survival rate improved significantly after 2002, especially in cases of "localized" and "adjacent organs" disease; this was likely due to the introduction of concurrent chemotherapy and radiation. The conditional 5-year relative survival rate improved significantly yearly until the fourth survival year. In the surgery-based group, we observed no age-dependent differences in outcomes. Unexpectedly, however, prognosis for younger age groups was poorer in the radiation-based treatment group. These results indicate that although relative survival rates have recently increased, treatment for more advanced cases with distant metastasis requires further improvement. In addition, this study is the first to suggest that age might be an important predictor of radiotherapy resistance in cervical cancer. Significance: A large-cohort analysis of cervical cancer cases reveals that age-adjusted incidence in Japan has increased since 2000 and that age may negatively correlate with resistance to radiotherapy.