title: Reduction of the incidence and mortality of rectal cancer by polypectomy: a prospective cohort study in Haining County.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Cancer Institute, Zhejiang University, 88 Jiefang Road, HangZhou 310009, Zhejiang Province, China. zhengshu@mail.hz.zj.cn
authors.forename: Shu
authors.initials: S
authors.lastname: Zheng
authors.forename: Xi-Yong
authors.initials: XY
authors.lastname: Liu
authors.forename: Ke-Feng
authors.initials: KF
authors.lastname: Ding
authors.forename: Lin-Bo
authors.initials: LB
authors.lastname: Wang
authors.forename: Pei-Lin
authors.initials: PL
authors.lastname: Qiu
authors.forename: Xin-Feng
authors.initials: XF
authors.lastname: Ding
authors.forename: Yong-Zhou
authors.initials: YZ
authors.lastname: Shen
authors.forename: Gao-Fei
authors.initials: GF
authors.lastname: Shen
authors.forename: Qi-Rong
authors.initials: QR
authors.lastname: Sun
authors.forename: Wei-Dong
authors.initials: WD
authors.lastname: Li
authors.forename: Qi
authors.initials: Q
authors.lastname: Dong
authors.forename: Su-Zhan
authors.initials: SZ
authors.lastname: Zhang
mesh_terms: D000236:Adenoma / Q000601:surgery; D000328:Adult; D000368:Aged; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007417:Intestinal Polyps / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control* / Q000601:surgery