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Background:Screening of colorectal cancer (CRC) and colorectal adenoma (CRA), the precursor of CRC, is crucial for CRC prevention.It is believed that opportunistic screening of CRC in high risk population would narrow down the screening scope and save the health resources, and is suitable for the present status in China.Aims:To analyze the performance of high risk factors in predicting CRC/CRA, for exploring the feasibility of opportunistic screening for CRC in high risk population.Methods:A total of 1 862 outpatients and health examination subjects undergoing colonoscopy from Feb.2015 to Aug.2016 at the PLA 281 Hospital were recruited and asked to complete a questionnaire of high risk factors for CRC and CRA before colonoscopy.The questionnaire was designed based on the updated consensus on the screening and management of early colorectal cancer and precancerous lesion in China.Using the results of colonoscopy as gold standard, the predictive performance of high risk factors for CRC/CRA was analyzed.Results:Four hundred and sixty-eight (25.1%) individuals with high risk factors for CRC/CRA were screened out by the questionnaire.The detection rate of CRC in individuals with high risk factors was significantly higher than those without (17.5% vs.0.9%, P=0.000).The sensitivity, specificity, positive and negative predictive values of high risk factors in predicting CRC were 87.2%, 78.2%, 17.5% and 99.1%, respectively, and the missed diagnosis rate was 12.8%.For CRC/CRA, the corresponding figures were 83.2%, 87.0%, 57.3%, 96.1% and 16.8%, respectively.The risk ratios (RR) of high risk factors for CRC and CRC/CRA were 20.35 and 14.78, respectively.Conclusions:Opportunistic screening of CRC in high risk population is feasible and applicable in China under present condition.
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Background:Detection and removal of colorectal polyp by colonoscopy is of great importance for prevention of colorectal carcinoma. Aims:To investigate whether the clinical symptoms of patients undergoing colonoscopy may hint colorectal polyp and carcinoma,and provide reference for candidate selection in colonoscopic screening. Methods:A total of 2 366 patients undergoing colonoscopy were recruited and the history information such as symptoms at outpatient visits, site and nature of the lesions was collected for analyzing the detection rates of colorectal polyp and carcinoma and the correlations of clinical symptoms with the risk and site of the disease. Results:The overall detection rates of colorectal polyp and carcinoma were 20. 5% and 5. 4% ,respectively,in 2 366 patients. The detection rates were significantly higher in symptomatic patients than those in asymptomatic patients(24. 2% vs. 4. 5% for polyp and 6. 4% vs. 0. 9% for carcinoma,P all = 0. 000). Moreover,when patients were classified by major symptoms,the detection rate of colorectal polyp was significantly increased in patients with diarrhea(OR = 1. 213),hematochezia(OR = 2. 076),and changing of stool consistency(OR = 1. 503)(P all < 0. 05),and the detection rate of colorectal carcinoma was significantly increased in patients with abdominal pain( OR = 1. 568),hematochezia( OR = 2. 837),changing of stool consistency( OR =2. 206),and tenesmus( OR = 1. 735)( P all < 0. 05). The major symptoms being hematochezia,changing of stool consistency and tenesmus were associated with lesions locating at rectum or left hemicolon(P all < 0. 05). Conclusions:Diarrhea, hematochezia and changing of stool consistency hints risk for colorectal polyp, while abdominal pain, hematochezia,changing of stool consistency and tenesmus hints risk for colorectal carcinoma. Colonoscopy is strongly recommended for patients with these symptoms.