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Background: Colorectal cancer is the third most common cancer in the world, arising mostly from pre-existing adenomatous polyps (adenomas) of the large bowel. Patients with colorectal adenomas are at increased risk of colorectal cancer because of a high recurrence rate for adenomas. We followed a cohort of 1490 patients with rectal adenomas to determine whether recurrence might be related to pathologic characteristics of the initial adenomas.Methods: The patients were identified in Haining County, China, from 1977 through 1978 by means of examination with a 15-cm rigid sigmoidoscope. They were followed by endoscopic examination at years 2, 4, 6, 11, and 16 after their initial polypectomy. New adenomas in the rectum were identified in 280 patients in these follow-up examinations.Results: Statistically significant twofold to threefold elevated risks of metachronous (recurrent) adenomas were observed for patients who had more than two initial adenomas or whose most advanced initial adenoma was more than 1.0 cm in size, was of villous/tubulovillous type, or showed moderate to severe dysplasia. Much stronger associations were observed for advanced metachronous neoplasms, which are defined as cancers or adenomas with severe dysplasia, with multivariate adjusted relative risks (95% confidence interval) of 4.2 (1.8-9.9) for a large initial adenoma (>1.0 cm), 8.1 (4.2-15.6) for villous/tubulovillous architecture, and 14.4 (5.0-41.3) for severe dysplasia. In particular, patients who had a large (>1.0 cm) adenoma with severe dysplasia at baseline had a relative risk of 37 (7.8-174.7) of developing advanced metachronous neoplasms compared with patients who had small adenoma(s) with mild dysplasia.Conclusions: The risk of metachronous adenomas is closely related to the pathology of initial adenomas, thus allowing identification of a high-risk group of adenoma patients for close surveillance after their initial polypectomy. [ABSTRACT FROM AUTHOR]

Objective: To compare the performances of fecal occult blood quantitive testing instrument and colloidal gold strip method in colorectal cancer screening., Methods: A representative random population of 9000 subjects aging between 40 and 74 years old were selected from Xuxiang, Haining city, Zhejiang province, by random cluster sampling method in year 2011. The fecal samples from each subject were separately detected by the two methods, namely fecal occult blood quantitive testing instrument and colloidal gold strip method. The positive result was standardized by hemoglobin concentration (HGB) ≥ 100 ng/ml under the application of quantitive testing instrument, or color-developing by colloidal gold strip method. The positive subjects from either method would be provided a further colonoscopy examination for pathological diagnosis. The positive rate and consistency of the two methods were compared, as well as the positive predictive value and population detecting rate of the colorectal cancer and adenoma., Results: A total of 6475 (71.9%) subjects submitted their two fecal samples according to our requirement in 9000 subjects. There were separately 319 positive cases (4.9%) and 146 positive cases (2.3%) by the performances of fecal occult blood quantitive testing instrument and colloidal gold strip method, including 45 positive in both tests (Kappa = 0.168, 95%CI:0.119-0.217).184 out of the 319 positive cases (57.7%) in the test by quantitive testing instrument and 89 out of 146 positive cases (61.0%) in the test by colloidal gold strip method received the colonoscopy examination. There were no significant statistical differences between the two methods in the positive predictive value of colorectal cancer (P > 0.05) , developing adenoma and non-developing adenoma.However, the population detecting rate of the colorectal cancer and developing adenoma were higher in the test by quantitive testing instrument (26 cases, 0.402%) than it in the test by colloidal gold strip method (10 cases, 0.154%). The difference showed statistical significance (χ(2) = 7.131, P < 0.01)., Conclusion: The performances of fecal occult blood quantitive testing instrument might be better than colloidal gold strip method in colorectal cancer screening. However, the results need to be further verified.

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.