Completeness of cancer registry data in a small Iranian province: A capture–recapture approach

Background and Objective: The incidence of cancer is rising in Iran, and hence it is important to assess the accuracy of the Iranian cancer registry dataset. In this study, the completeness of the cancer registry in the Kohgiluyeh and Boyer-Ahmad (K&B) province is evaluated. Method: The data of registered cases of cancer of people who were living in the K&B province at the time of diagnosis were obtained from the provincial cancer registry offices in K&B, Fars and all other neighbouring provinces. A capture–recapture method along with log-linear statistical modelling were used for analysis. Results: The results indicated that of 2029 known cases of cancer, only 1400 (31%) were registered by the K&B cancer registry office. Age-adjusted incidence rates for all common types of cancer rose from 307.0 per 100,000 (95% confidence interval (CI); 293.8, 320.3, based on observed cases) to 376.4 per 100,000 (95% CI; 361.7, 391.1, based on expected number of cases estimated by capture–recapture analysis) (p < 0.01). The completeness of cancer registry data varied significantly for different types of cancer. Conclusion: Results suggest that the provincial cancer dataset, which is a part of the national cancer registry programme, is neither complete nor representative. A major improvement in case finding, registry procedures and effective data sharing by provincial cancer registry offices is needed in order to provide valid data for epidemiology of cancer in Iran.