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U.S. National Institutes of Health National Cancer Institute

2007 Multiple Primary and Histology Coding Rules
Revised May 6, 2008

The 2007 Multiple Primary and Histology Coding Rules present the first site-specific multiple primary and histology rules developed to promote consistent and standardized coding by cancer registrars. See Registrar Training to view recordings and transcripts of the MP/H Rules Breeze-online training sessions.

This project was sponsored by the National Cancer Institute's SEER Program. In January 2003, the Multiple Primary and Histology Task Force (MP/H Task Force) was formed to tackle problems identified in existing rules. The MP/H Task Force was a diverse group with membership from all but two SEER regions, the American College of Surgeons (ACoS) Commission on Cancer (CoC), the American Joint Committee on Cancer (AJCC), the Centers for Disease Control and Prevention (CDC) National Program of Cancer Registries (NPCR), the National Cancer Registrars Association (NCRA), North American Association of Central Cancer Registries (NAACCR), 15 central registry representatives, and Statistics Canada. Physician guidance by specialty pathologists and clinicians was integral to the review and revision process. Regular consultation with the editors of ICD-O-3 clarified ICD-O-3 codes and ensured that the new rules accurately reflect the ICD-O-3 intent and purpose.

The 2007 Multiple Primary and Histology Coding Rules contain site-specific rules for lung, breast, colon, melanoma of the skin, head and neck, kidney, renal pelvis/ureter/bladder, benign brain, and malignant brain. A separate set of rules addresses the specific and general rules for all other sites. The multiple primary rules guide and standardize the process of determining the number of primaries. The histology rules contain detailed histology coding instructions. For example, grouping histologic terms, differentiating between general (NOS) terms and specific histologic types and subtypes, and identifying mixed and combination codes are covered. The MP/H Task Force also developed three new data items that complement these rules.