A novel approach to estimate the German-wide incidence of testicular cancer

Background: Currently, only 7 out of 16 Federal States of Germany provide testicular cancer incidence rates with an estimated completeness of at least 90% which complicates the regional comparison of incidence rates. The aim of this study was to provide a novel approach to estimate the testicular cancer incidence in Germany by using nationwide hospitalization data. Methods: We used the nationwide hospitalization data (DRG statistics) of the years 2005-2006 including 16,6 million hospitalizations among men. We identified incident testicular cancer cases by the combination of a diagnosis of testicular cancer and an orchiectomy during the same hospitalization and estimated the age-specific and age-standardized (World Standard Population) incidence of testicular cancer across Federal States. We also analyzed available cancer registry data from 2005 to 2006. Results: A total of 8544 hospitalizations indicated incident testicular cancer cases in 2005-2006. The nationwide crude incidence rate of testicular cancer was 10,6 per 100.000 person-years. The ratio of the number of registered cases (cancer registry) to the estimated number of cases based on the hospitalization statistics ranged between 79% and 100%. There was only little variation of the age-standardized DRG-based incidence estimates across Federal States (range: 8,2-10,6 per 100.000 person-years). Discussion: We provided testicular cancer incidence estimates for each of the 16 Federal States of Germany based on hospitalization data for the first time. The low within-population incidence variability in Germany and high between-population incidence variability in Europe may indicate that ecologic factors play a causal role in the European variation of testicular cancer.