A Study on the Effectiveness of Mass Screening for Cancer Using the Prefectural Cancer Registry

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Purpose: We conducted a survival analysis to assess the effectiveness of mass screening program for gastric, cervical, lung, intestinal, and breast cancers in Saga Prefectural using the data from the Saga Prefectural Cancer Registry.Methods: We utilized the data of the Saga Prefectural Cancer Registry from January, 1982 to December, 1996. We defined the screened group as patients whose cancer was first detected by the screening program, and assigned residual patients to the non-screened group. The number of cancer case in the screened and the non-screened group, were as follows, respectively: 1,451 and 8,325 of gastric cancer, 188 and 817 of cervical cancer, 544 and 3,778 of lung cancer, 210 and 4,537 of intestinal cancer, and 85 and 1,847 cases of breast cancer. We compared the 14-years cumulative survival rates of the screened group to those of the non-screened group by cancer site. Hazard ratios and their 95% confidence intervals for mortality regarding screening program were estimated with the Cox' proportional hazard model.Results: The screened group showed the significantly higher 14-years cumulative survival rates than the non-screened group regarding each screening program for gastric, cervical, lung, intestinal, and breast cancer. The risk in mortality was significantly decreased when cancer was detected by the screening program. The age and sex-adjusted hazard ratios (and their 95 % confidence intervals) for mortality of the screening program were 0.40 (0.36-0.44) for gastric cancer, 0.41 (0.27-0.62) for cervical cancer, 0.51 (0.45-0.57) for lung cancer, 0.45 (0.32-0.62) for intestinal cancer, and 0.43 (0.20-0.90) for breast cancer.Conclusion: Mass screening program for gastric, cervical, lung, intestinal, and breast cancer is thought to be effective in terms of 14-years cumulative survival rates according to the Saga Prefectural Cancer Registry.