Which resource is necessary for determining how many primaries to accession by the registrar?

The Multiple Primary and Histology Rules are essential for determining how many primary tumors should be accessioned by the registrar. These rules provide detailed guidelines for classifying tumors when a patient has more than one primary cancer, which is critical for accurate cancer registry reporting. The rules help registrars decide whether to consider tumors as separate primaries or to combine them, ensuring consistency and accuracy in cancer data collection.

Each type of cancer can have distinct criteria based on factors like histology, behavior, and site, which the Multiple Primary and Histology Rules delineate thoroughly. By following these rules, registrars can properly identify and document each distinct primary tumor, which is paramount for effective cancer surveillance and epidemiological studies.

Other resources, while essential in their own ways, do not specifically focus on the criteria for identifying multiple primaries. The SEER Program Coding and Staging Manual, for example, provides valuable information for coding and staging cancers, but does not detail the complexities of multiple primaries. Similarly, NAACCR standards focus on data exchange and quality for cancer registries, and ICD-O, 3rd edition, primarily serves as a coding system for the diagnosis of tumors. Thus, the Multiple Primary and Histology Rules stand out as the necessary resource