Completeness of information on adjuvant therapies for colorectal cancer in population-based cancer registries

BACKGROUND: Population-based cancer registries represent a potentially valuable tool to evaluate treatment; however, information on the completeness of registry treatment data is sparse. OBJECTIVE: To evaluate the completeness of registry treatment data for patients with colorectal cancer and to identify predictors of complete reporting. RESEARCH DESIGN: We surveyed physicians or reviewed office records of 1956 northern California patients diagnosed with colorectal cancer during 1996 to 1997 to assess the completeness of registry data regarding use of adjuvant chemotherapy and radiation therapy. RESULTS: For patients with a record of receipt of chemotherapy in either the registry or physician survey, information was in the original registry records for 82.0%. In the multivariate analysis, completeness of chemotherapy reporting was lower for patients aged 65 to 74, those with colon cancer, corrected] and higher for patients treated in hospitals that are part of a large health maintenance organization (HMO). For patients with a record of receipt of radiation therapy, information was in the original registry records for 90.2%. In the multivariate analysis, completeness of radiation therapy reporting was higher for patients aged 18 to 54 and those treated in HMO hospitals. CONCLUSIONS: Because the completeness of the registry treatment data varied by patient and hospital characteristics, use of registry data without supplementation could bias estimates of the proportion of patients treated, and of the patient and provider characteristics associated with treatment. Enhanced cancer registry data could be a valuable component of population-based cancer data systems for assessing quality of cancer care.