Disclaimer. This site is a training resource for oncology data specialists and cancer registration trainees. It is not intended to provide medical advice or to guide clinical care, diagnosis, or treatment. NCI urges users to consult with a qualified physician for diagnosis and for answers to their personal medical questions.

Providing web-based training modules for cancer registration and surveillance

Table D

Reasons for Possible Change of Reference Date

Changes in population or census
Inconsistencies or lapse in the database
High lost-to-follow-up rate
Changes in data acquisition methods
Lack of staffing for an extended period

Return to Reference Date

Suggested Citation

SEER Training Modules: Table D. U.S. National Institutes of Health, National Cancer Institute. Cited 08 January 2026. Available from: https://training.seer.cancer.gov.

Table D

Reasons for Possible Change of Reference Date

Suggested Citation

Glossary Term