Routine practice data of three cancer entities: Comparison among cancer registry and health insurance data

Introduction: Claims data and cancer registry data are valuable secondary data sources for addressing health service research questions. This study provides a thorough insight into the comparability of data from health insurance companies and cancer registries in Germany regarding breast, prostate, and lung cancer patients and their treatment.Methods: For this study claims data of the InGef database and data of the Cancer Registry of Rhineland-Palatinate were used to identify patients living in Rhineland-Palatinate with an incident breast, prostate, or lung cancer diagnosis between Jan. 1, 2018 and Dec. 31, 2019. Both datasets were compared for patient and tumour characteristics as well as treatment strategy. For the descriptive analysis of tumour localisa-tion and treatment all patients were followed up for a maximum of two years.Results: A total of 1,470 incident cancer cases were identified in the InGef database and 1,694 in the Cancer Registry. Data on sex, age, and tumour localisation matched well for all cancer entities in the cohorts. Data for early UICC stages I+II varied between the cohorts for prostate cancer (84% InGef, 66% Cancer Registry) and lung cancer (29% InGef, 20% Cancer Registry). Larger deviations were found for antihormonal treatment (breast 54% vs. 44%, prostate 32% vs. 18%). Significant differences were found for surgery (breast and lung) and radiation (breast and prostate), respectively. Discussion: Age at diagnosis, tumour localisation, and treatment for breast cancer was well documented in both databases. Tumour-specific deviations were observed for tumour localisations (lung cancer), UICC stage (prostate and lung cancer) and treatment options.Conclusion: Both databases show very good completeness across cancer entities, but at the same time have minor limitations where they could readily complement each other. Individual linkage of claims and registry data could be an important step to improve oncological studies with routine practice data and to overcome the limitations identified.