Incidence of advanced colorectal cancer in Germany: comparing claims data and cancer registry data

BACKGROUND: Incidence rates of advanced cancer stages are important, e.g., for monitoring cancer screening programs. However, information from cancer registries on tumor stage is often incomplete. Exemplified by colorectal cancer (CRC), we explored the potential of German claims data to estimate incidence rates of advanced cancer stages. METHODS: We used claims data of the German Pharmacoepidemiological Research Database (GePaRD; information on > 20 million persons) to identify incident patients with advanced CRC based on ICD-10 codes for CRC and secondary malignant neoplasms. We calculated annual age-standardized incidence rates (ASIRs) of advanced CRC per 100,000 for the years 2008-2015 stratified by the presence of affected lymph nodes only (C77) vs. distant metastases (C78-C79) and compared them to ASIRs determined using data (2008-2014) from the German Centre for Cancer Registry Data (ZfKD). RESULTS: In GePaRD, the ASIRs of advanced CRC per 100,000 in 2014 were 21.5 among men and 14.9 among women. Compared to ZfKD data the ASIR in GePaRD was 2.58 lower in men and 0.27 higher in women (per 100,000) in 2014. Stratification by presence of distant metastases showed divergent patterns: the ASIRs regarding distant metastases were ~ 50% (women) and ~ 30% (men) higher, and the ASIRs regarding affected lymph nodes only were ~ 40% lower in GePaRD as compared to ZfKD. CONCLUSION: While ASIRs of advanced CRCs overall agreed well between claims and cancer registry data in 2014, the analyses stratified by presence of distant metastases showed differences. Cancer registries might underestimate ASIRs of CRCs with distant metastases.