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.

Membership includes: