Completeness of regional cancer registry data in Northwest Russia 2008-2017

BACKGROUND: A national framework for population-based cancer registration was established in Russia in the late 1990s. Data comparability and validity analyses found substantial differences across ten population-based cancer registries (PBCRs)in Northwest Russia, and only four out of ten met international standards. This study aimed to assess the completeness of the PBCR data of those registries. METHODS: Qualitative and quantitative methods recommended for completeness and timeliness assessment were applied to the data from ten Russian regional PBCRs in Northwest Russia, covering a population of 13 million. We used historic data methods (using several European PBCRs reference rates), mortality-to-incidence ratios (M:I) comparison, and death certificate methods to calculate the proportion of unregistered cases (Lincoln-Petersen estimator and Ajiki formula). RESULTS: Incidence rate trends of different cancer types were stable over time (except one region - Leningrad oblast). A slight drop in incidence rates in older age groups for several sites in the Northwestern regions was observed compared to the reference from European countries. Comparing M:I ratios against five-year survival revealed systematic differences in Leningrad oblast and Vologda oblast. Assessment of completeness revealed low or unrealistic estimates in Leningrad oblast and completeness below 90% in St. Petersburg. In other regions, the completeness was above 90%. The national annual report between 2008-2017 did not include about 10% of the cases collected later in the registry database of St. Petersburg. This difference was below 3% for Arkhangelsk oblast, Murmansk oblast, Novgorod oblast, Vologda oblast and the Republic of Karelia. CONCLUSIONS: Eight out of ten regional PBCRs in Northwest Russia collected data with an acceptable degree of completeness. Mostly populated St. Petersburg and Leningrad oblast did not reach such completeness. PBCR data from several regions in Northwest Russia are suitable for epidemiological research and monitoring cancer control activities. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12885-023-11492-z.