Background: The regulations of the Norwegian Patient Register (NPR) and the Cancer Registry of Norway (CRN) allow linkage of the registries for evaluation of completeness and validity of data.
Material and method: Data on patients registered as having C18 (colon cancer), C19-C21 (cancer of the rectum, rectosigmoid junction or anus), C33-C34 (cancer of the lungs or trachea), C50 (breast cancer), C61 (prostate cancer) or C66-C68 (cancer of the bladder, ureter or urethra) were obtained from NPR 2008 and compared with data from CRN.
Results: 81 % of patients registered in NPR as having colon cancer were registered with the same diagnosis in CRN. Corresponding figures were 94 % for breast cancer (women), 97 % for prostate cancer, 82 % for cancer of the rectum, rectosigmoid junction or anus, 93 % for urinary tract cancer and 90 % for cancer of the lungs or trachea. In cases where NPR codes and CRN diagnoses did not match, a related diagnosis was often registered in the CRN.
Interpretation: The agreement between the data in NPR and CRN is relatively good for the diagnoses included in the study. The NPR codes are less precise for colon and rectal cancer than for the other major types of cancer. Regular exchange of data between the registries will further improve the quality of the data.