Emerging Themes in Epidemiology

Background: The aim of this study was to provide a novel approach for estimating the incidence of renal cancer in Germany by using hospitalization data from the years 2005–2006 and to compare these estimates with incidence rates from cancer registries. We used nationwide hospitalization data from the years 2005–2006 including 34.2 million hospitalizations. We used three definitions of potential incident renal cancer cases: 1) a main or secondary diagnosis of renal cancer and a partial or total nephrectomy; 2) a main diagnosis of renal cancer and a partial or total nephrectomy; and 3) a main diagnosis of renal cancer (without a secondary diagnosis of renal pelvis cancer) and a partial or total nephrectomy. In addition, we used cancer registry data for comparison of rates. Results: Hospitalization data to which definition 2 applied provided incidence rate estimates nearly identical to those provided by the cancer registries (when the cases registered from death certificates only were excluded). Age-standardized (European standard population) incidence rates based on hospitalization data and cancer registry data were 15.6 per 100 000 and 15.7 per 100 000 among men and 8.0 per 100 000 and 7.6 per 100 000 among women respectively. Cancer registry-based incidence rates were lower especially among those federal states with an estimated completeness of registration below 90% (Berlin and Saxony-Anhalt). Conclusions: Representative hospitalization data can be used to estimate incidence rates of renal cancer. We propose that incidence rates can be estimated by hospitalization data if 1) the primary treatment is performed during an in-hospital stay and 2) nearly all patients undergo a defined surgical procedure that is not repeated for the treatment of the same cancer. Our results may be useful for countries with no or incomplete cancer registration or for countries that use hospitalization data to provide a representative incidence of renal cancer.