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

目的：我们利用佐贺县癌症登记处的数据，对佐贺县胃癌、宫颈癌、肺癌、肠癌和乳腺癌的大规模筛查计划的效果进行生存分析。我们将筛查组定义为筛查程序首次发现癌症的患者，并将剩余患者分配到未筛查组。筛查组和未筛查组癌症病例数分别为：胃癌1451例和8325例，宫颈癌188例和817例，肺癌544例和3778例，肠癌210例和4537例，乳腺癌85例和1847例。我们根据肿瘤部位比较了筛查组和未筛查组的14年累积存活率。结果：在胃癌、宫颈癌、肺癌、肠癌和乳腺癌的筛查中，筛查组的14年累计生存率显著高于未筛查组。当筛查程序检测到癌症时，死亡风险显著降低。经年龄和性别调整的风险比(及其95%可信区间)：胃癌0.40(0.36~0.44)，宫颈癌0.41(0.27~0.62)，肺癌0.51(0.45~0.57)，肠癌0.45(0.32~0.62)，乳腺癌0.43(0.20~0.90)。根据佐贺县癌症登记处的数据，就14年累计生存率而言，乳腺癌被认为是有效的。

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.