California Cancer Reporting System Standards Volume I: Abstracting and Coding Procedures for Hospitals
For cases diagnosed January 1, 2005 through December 31, 2006, apply the SEER Multiple Primary and Histology Rules as written in the SEER Program Coding and Staging Manual, 2004.
For cases diagnosed prior to January 1, 2005, the following are to be considered separate primaries:
A new cancer with the same histology and behavior as an earlier one, if diagnosed in the same site after two months, unless stated to be recurrent or metastatic.
Exception #1: For bladder cancers with site codes C67.0-C67.9 and morphology codes 8120 8130 and adenocarcinomas of the prostate (C61.9), a single report of the first invasive lesion only is required.
Exception #2: If there is an in situ followed by an invasive cancer in the same site more than two months apart, report as two primaries even if noted to be a recurrence. The invasive case must be diagnosed 1/1/95 or later. Effective with cases diagnosed January 1, 1998, and later, this also applies to bladder and prostate sites. For these two sites, the first invasive case must be diagnosed 1/1/98 and later. The purpose of this guideline is to ensure that a case is counted as an incidence case, i.e., invasive, when data are analyzed by the regional and central registry.
Multiple lesions of different histologic types in the same site, whether occurring simultaneously or at different times. (Note: Different histologic terms are sometimes used to describe progressive stages or phases of the same disease process.)
Multiple lesions of different histologic types in different sites.
See also:
Section II.1.3.6 Lymphatic and Hematopoietic Diseases - Subsequent Diagnoses