The NCDB uses which method to identify duplicate cases?

• A. The patient's name
• B. The patient's Social Security number
• C. The patient's primary site and histology
• D. A contextual code based on specific data item code values from the record

Answer: (D)

In the NCDB, identifying duplicate cases is done by generating a contextual code from the record’s data items, rather than relying on personal identifiers. This contextual code acts as a unique signature based on specific values within the record (such as patient demographics and tumor details), which allows the database to flag potential duplicates across submissions while protecting patient privacy. Names and Social Security numbers are either unreliable for matching or not used due to privacy and data quality concerns, and matching on primary site and histology alone isn’t enough to distinguish different patients. The contextual code combines multiple data items to create a robust identifier that helps detect the same case reported from multiple sources.