California Cancer Reporting System Standards Volume I: Abstracting and Coding Procedures
Each reporting facility must maintain its own roster of physicians and their code or NPI numbers. The non-NPI numbers codes are based on the physicians' California license numbers.
As physicians who treat cancer patients join the reporting facility's staff, they must be added to the roster with their license or NPI numbers. If the license number is unavailable, assign a temporary number, beginning it with the letter X to differentiate it from regular codes. When the license number becomes available, update the files as soon as possible.