What is data reconciliation (deduplication) in cancer registry data, and why is it important?

• A. Merging records that refer to the same patient/cancer to avoid duplicates and ensure accurate counts
• B. Splitting records that refer to different patients
• C. Deleting all records older than 5 years
• D. Archiving all duplicates

Answer: (B)

Data reconciliation (deduplication) is the process of identifying multiple records that describe the same patient or cancer event and merging them into a single, authoritative record. This prevents duplicates from inflating counts and ensures accurate incidence, trends, and analyses. Registrars use matching rules—comparing identifiers like names, dates of birth, diagnosis dates, tumor site, facility, and medical record numbers—to decide when two records belong to one case. The result is a master record that consolidates all verified information without double counting. This helps ensure data quality, reliable statistics, and correct patient follow-up. Splitting records, deleting old records, or archiving duplicates do not achieve this unifying effect; they either fragment data, discard information, or preserve redundancy rather than eliminating it.