Estimating the Esophagus Cancer Incidence Rate in Ardabil, Iran: A Capture-Recapture Method

BACKGROUND Accurate cancer registry and awareness of cancer incidence rate is essential in order to define strategies for cancer prevention and control programs. Capture-recapture methods have been recommended for reducing bias and increase the accuracy of cancer incidence estimation. OBJECTIVES This study aimed to estimate the esophagus cancer incidence by capture-recapture method based on Ardabil population-based cancer registry data. PATIENTS AND METHODS Total new cases of esophagus cancer reported by three sources of pathology reports, medical records, and death certificates to Ardabil province cancer registry center in 2006 and 2008 were enrolled in the study. All duplicated cases between three sources were identified and removed using Excel software. Some characteristics such as name, surname, father's name, date of birth and ICD codes related to their cancer type were used for data linkage and finding the common cases among three sources. The incidence rate per 100,000 was estimated based on capture-recapture method using the log-linear models. We used BIC, G(2) and AIC statistics to select the best-fit model. RESULTS After removing duplicates, total 471 new cases of esophagus cancer were reported from three sources. The model with linkage between pathology reports, medical record sources and independence with the death certificates source was the best fitted model. The reported incidence rate for the years 2006 and 2008 was 18.77 and 18.51 per 100,000, respectively. In log-linear analysis, the estimated incidence rate for the years 2006 and 2008 was 49.71 and 53.87 per 100,000 populations, respectively. CONCLUSIONS Based on the obtained results, it can be concluded that none of the sources of pathology reports, death certificates and medical records individually or collectively were fully covered the incidence cases of esophagus cancer and need to apply some changes in data abstracting and case finding.