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History of Multiple Primaries & Histology Coding Rules Committee

Establishment of Histology Committee

In January 2003, the Multiple Primary and Histology Coding Committee (Histology Committee) was formed to tackle problems identified in existing rules.

The NAACCR May 2003 publication of "A Review of the Definition for Multiple Primary Cancers in the United States", taken from workshop proceedings in December 2002, highlighted the multiple primary rules and listed specific recommendations and comments that proposed reviewing, clarifying and possibly revising the rules. In December 2003, the NAACCR Record Consolidation Committee issued a "Report to the NAACCR Board", following the "Creation of a Record Consolidation Test File", which confirmed wide variability among state and regional central cancer registries in the use of SEER rules for determining multiple primaries. Tumors were counted and reported differently, depending upon how the general rules were applied.

Phase I of the rule development process consisted of eight sets of site-specific rules and a set of rules covering all other sites. The development process occurred between January 2003 and late 2005. During 2006, SEER and other cancer surveillance partners continued the development process by

  • Conducting field trials to refine the rules and their adaptation within registry operations
  • Producing educational materials and facilitating a national training program.

The Rules Development Process

The development of the new rules involved several steps. New site-specific rules were drafted and reviewed by the committee. At the same time, cases were requested and prepared for testing the rules. The revised draft rules were reviewed by the Histology Committee until approved. Several revisions of the rules were made, based on the pre-test comments and results. The functionality and usability of the new multiple primary and histology rules were beta-tested through a series of "mini-reliability studies" focusing on the separate cancer sites. The reliability studies included single tumors and multiple tumors. Cases included most common histology groups and subtypes for cancer, including divisions of major and minor histology types. Reliability studies also included instructions on how to use combination codes for the histologies. The 2006 field trial further refined the implementation processes in registry operations, informatics, and statistical reporting of cancer incidence.

Concerns that were raised regarding the impact of the new rules on statistics (incidence rates) were addressed in a series of meetings with National Cancer Institute statisticians who use the population-based data on a daily basis. In addition, the use of new data items such as multiplicity and ambiguous terminology was tested in central registries and facility-based registries.