General Multiple Primary Rules

Solid Tumors

The SEER 2018 Solid Tumor Rules are effective with cases diagnosed on or after January 1, 2018.  They contain site-specific rules for Head & Neck, Colon, Cutaneous Melanoma, Lung, Breast, Kidney, Urinary Sites, Malignant CNS & Peripheral Nerves, Non-Malignant CNS Tumors and Other Sites.    The purpose of these rules is to determine multiple primaries and to code histology only  They are not used to determine case reportability, casefinding, stage, or tumor grade.  The complete Solid Tumor Rules may be downloaded from the SEER web site at: https://seer.cancer.gov/tools/solidtumor/

Please note:  The content in the Solid Tumor Rules are cumulative. For cases diagnosed after 2018, utilize the most current manual for all solid tumors. The SEER Solid Tumor Rules do not apply to hematopoietic primaries (lymphoma and leukemia M9590-9989). 

Use the Site-specific rules for the following primary site groups:

• Head and Neck
• Colon (includes rectosigmoid and rectum)
• Cutaneous Melanoma (2021+)
• Lung
• Breast
• Kidney
• Urinary Sites
• Malignant CNS and Peripheral Nerves
• Non-Malignant CNS
• Other Sites (2023+)  Use for solid malignant tumors that occur in primary sites not covered by site-specific rules. For cases between 2007-2022, use the 2007 MPH Other Sites.

For solid tumors diagnosed January 1, 2007 through December 31, 2017 use the 2007 SEER MP/H Rules Manual.

For solid malignant tumors and benign/borderline brain tumors diagnosed before 2007, use the SEER Multiple Primary Rules below, which are based on the International Classification of Diseases for Oncology (ICD-O-3), to determine if a diagnosis is a single or multiple primary

1. Use the definitions below under the heading "Primary Site" to decide whether the tumor(s) involve one site or multiple sites.
2. Follow the instructions under the heading "Rules for Coding Histology of Solid Tumors Diagnosed Prior to 2007" in item #30090 (Histology) to decide whether the tumor(s) are a single histology or mixed/multiple histologies.
3. Use the"Rules for Determining Multiple Primary Cancers" to decide whether the case should be abstracted as one primary or multiple primaries.

1.  Definitions for determining a single site and a single histology.

Primary Site

A single site is defined as the same first three characters in the topography code for the sites listed below:

EXAMPLE: The trigone of bladder (C67.0) and lateral wall of bladder (C67.2) are considered subsites of the bladder, and would be treated as one site. A tumor or lesion involving both subsites would be coded either to overlapping sites of bladder (C67.8), or bladder, NOS (C67.9).

A single site is defined as the same fourth character in the topography code for the anatomic sites listed below:

EXAMPLE: The transverse colon (C18.4), and the descending colon (C18.6), are considered separate sites. The only EXCEPTION to this is familial polyposis or polyposis coli involving more than one segment of the colon. This is abstracted as only one primary, coded to colon, NOS (C18.9). If the familial polyposis involves both the colon and the rectum, abstract as one primary with site code C19.9.

A single site involves more than one three character category in the topography coding scheme for the anatomic sites listed below:

EXAMPLE: Base of tongue (C01.9), and border of tongue (C02.1), are considered subsites of the tongue, and would be treated as one site - either overlapping lesion of tongue (C02.8) or tongue, NOS (C02.9).

Each side of a paired organ is considered a separate site. Tumors arising on different sides of a paired organ are considered separate primaries, unless the tumor on one side is stated to be metastatic. Exceptions are bilateral involvement of the ovaries in which a single histology is reported, bilateral retinoblastomas, and bilateral Wilms' tumors, which are all considered single primaries.

Hematopoietic Malignancies

New reportability instructions and data collection rules for hematopoietic and lymphoid neoplasms go into effect for cases diagnosed beginning January 1, 2010. The Hematopoietic Database is an electronic tool developed to assist in screening for reportable cases and determining reportability requirements, as well as determination of multiple primaries. The database contains abstracting and coding information for all hematopoietic and lymphoid neoplasms (9590/3-9992/3).

Two tools have been developed for use beginning in 2010:

• The Hematopoietic and Lymphoid Neoplasm Case Reportability and Coding Manual
• The Hematopoietic Database

The Hematopoietic and Lymphoid Neoplasm Case Reportability and Coding Manual is embedded in the Hematopoietic Database (Hematopoietic DB). This manual contains reportability instructions and rules for determining the number of primaries, the primary site and histology, and the cell lineage or phenotype. The manual also includes several appendices. Use the instructions and rules within the manual first. The Hematopoietic DB is used when the rules specifically instruct the abstractor to refer to the DB or when the registrar has used all of the rules in the manual.  The manual was last updated September 2020.

The manual and database are available online and for download from the SEER web site:   http://seer.cancer.gov/tools/heme/index.html.