The reliability of multi‐source data linkage for population‐based cancer survival estimates: A study in a metropolitan cancer registry of China

Abstract Background Population‐based cancer survival is a key metric in evaluating the overall effectiveness of health services and cancer control activities. Advancement in information technology enables accurate vital status tracking through multi‐source data linkage. However, its reliability for survival estimates in China is unclear. Methods We analyzed data from Dalian Cancer Registry to evaluate the reliability of multi‐source data linkage for population‐based cancer survival estimates in China. Newly diagnosed cancer patients in 2015 were included and followed until June 2021. We conducted single‐source data linkage by linking patients to Dalian Vital Statistics System, and multi‐source data linkage by further linking to Dalian Household Registration System and the hospital medical records. Patient vital status was subsequently determined through active follow‐up via telephone calls, referred to as comprehensive follow‐up, which served as the gold standard. Using the cohort method, we calculated 5‐year observed survival and age‐standardized relative survival for 20 cancer types and all cancers combined. Results Compared to comprehensive follow‐up, single‐source data linkage overestimated 5‐year observed survival by 3.2% for all cancers combined, ranging from 0.1% to 8.6% across 20 cancer types. Multi‐source data linkage provided a relatively complete patient vital status, with an observed survival estimate of only 0.3% higher for all cancers, ranging from 0% to 1.5% across 20 cancer types. Conclusion Multi‐source data linkage contributes to reliable population‐based cancer survival estimates in China. Linkage of multiple databases might be of great value in improving the efficiency of follow‐up and the quality of survival data for cancer patients in developing countries.