Reduction of the incidence and mortality of rectal cancer bypolypectomy:a prospective cohort study in Haining County

AIM: To reduce the incidence and morlality of rectal cancerand address the hypothesis that colorectal cancer often arisefrom precursor lesion (s), either adenomas or non-alenomatous polyps, by conducting a population-basedmass screening for colorectal cancer in Haining County,Zhejiang, PRCMETHODS: From 1977 to 1980, physicians screened thepopulation of Haining County using 15 cm rigid endoscopy.Of over 240 000 participants, 4076 of them were diagnoselwith Precursor Iesions, eitler alenomas or non-adenomatous polyps, which were then removedl surgically.All individuals with precursor lesionswere followed up andreexamined by endoscopy every two to five years upto 1998.RESULTS: After the initial screening, 953 metactronousadenomas and 417 non-adenomatous polyps ware detected andremoved from the members of this cohort. Further, 27 cases ofcolorectal cancer were detected and treated. Log-rank tuestsshowed that the survival time among those cancer patients whounderwent mass screening increased significantly comparedtothat of other colorectal cancer patients (P ＜ 0.0001). Accordingto the population-based cancer registry in Haining County,age-adjusted incidence and mortality of rectal cancer decreasedby 41% and 29 % from 1977-1981 to 1992-1996, respectively.Observed cumulative 20-year rectal cancer incidence was 31%lower than the expected in the screened group; the mortalitydue to rectal cancer was 18 % lower thah the expected in thescreened group.CONCLUSION: Mass screening for rectal cancer andprecursor lesions with protocoscopy in the generalpopulation and periodical following-up with routineendoscopy for high-risk patients may decrease both theincidence and mortality of rectal cancer.

AIM: To reduce the incidence and mortality of rectal cancer and address the hypothesis that colorectal cancer often arise from precursor lesion(s), either adenomas or non-adenomatous polyps, by conducting a population-based mass screening for colorectal cancer in Haining County, Zhejiang, PRC. METHODS: From 1977 to 1980, physicians screened the population of Haining County using 15 cm rigid endoscopy. Of over 240000 participants, 4076 of them were diagnosed with precursor lesions, either adenomas or non-adenomatous polyps, which were then removed surgically. All individuals with precursor lesions were followed up and reexamined by endoscopy every two to five years up to 1998. RESULTS: After the initial screening, 953 metachronous adenomas and 417 non-adenomatous polyps were detected and removed from the members of this cohort. Further, 27 cases of colorectal cancer were detected and treated. Log-rank tests showed that the survival time among those cancer patients who under went mass screening increased significantly compared to that of other colorectal cancer patients (P<0.0001). According to the population-based cancer registry in Haining County, age-adjusted incidence and mortality of rectal cancer decreased by 41% and 29% from 1977-1981 to 1992-1996, respectively. Observed cumulative 20-year rectal cancer incidence was 31% lower than the expected in the screened group; the mortality due to rectal cancer was 18% lower than the expected in the screened group. CONCLUSION:Mass screening for rectal cancer and precursor lesions with protocoscopy in the general population and periodical following-up with routine endoscopy for high-risk patients may decrease both the incidence and mortality of rectal cancer.