Use the Solid Tumor Rules to determine the number of primaries to abstract and the histology to code. The Solid Tumor Rules and General Instructions replace the 2007 Multiple Primary & Histology (MP/H) Rules for the following sites:

  • Breast
  • Colon (includes rectosigmoid and rectum for cases diagnosed 1/1/2018 forward)
  • Head & Neck
  • Kidney
  • Lung
  • Malignant CNS and Peripheral Nerves
  • Non-malignant CNS
  • Urinary Sites
  • Cutaneous Melanoma (for cases diagnosed 1/1/2021 and forward)
  • Other Sites (for cases diagnosed 1/1/2023 and forward)

Other Sites

The Other Sites Solid Tumor Rules should be used for cases diagnosed 1/1/2023 and forward.

For cases diagnosed 1/1/2007-12/31/2022, the 2007 MP/H and 2007 General Instructions are to be used, with a few exceptions.

The following primary sites are excluded from the Other Sites module for 1/1/2018 forward:

  • Rectosigmoid and rectum which are included in Colon Solid Tumor Rules
  • Peripheral nerves which are included in the Malignant CNS Solid Tumor Rules

Download the 2024 Solid Tumor Modules

Use the 2024 Solid Tumor Rules for all cases diagnosed 2018+ (except Melanoma and Other Sites; see start dates above).

Revision History

See change log for updates made in December 2023. Please see the Revision Archive for earlier changes.

Histology Coding Clarifications

On occasion, data collection requirements of AJCC and NCI SEER have resulted in conflicting cancer coding instructions for cancer registrars. For more information and specific instructions about reviewing cases already coded, please visit the Histology Coding Clarifications page.

Suggested Citation

Dickie L., Johnson, CH., Adams, S., Negoita, S. (December 2023). Solid Tumor Rules. National Cancer Institute, Rockville, MD 20850.