Initial Screening Of High-Risk Population For Colorectal Cancer And Survey On Application Of Colonoscopy

Colorectal cancer(CRC)is the most common malignant tumor of digestive system worldwide whose incidence is also increasing year by year in China.Most colorectal cancers evolve from adenomas,and the evolution from adenoma to adenocarcinoma will take a long time,which makes it possible for CRC screening.What’s more,the stage of CRC is closely associated with its prognosis and patients’ economic burden.Therefore,CRC screening in our country can achieve great social and economic benefits.In recent years,a “step-by-step” screening strategy has been consistently recommended by guidelines related to CRC screening in our country.In this strategy,the population is first screened by simple,non-invasive methods to identify the high-risk groups which will be referred to colonoscopy,so that colonoscopy resources can be effectively used.This research explored the screening methods of high-risk populations for colorectal cancer,and a questionnaire survey was conducted on the issues we found in the process of research and clinical practice,in order to provide data support for the development of CRC screening in our country.Part Ⅰ Predictive Value of a Colorectal Neoplasia Risk-Scoring SystemCombined with Fecal Immunochemical TestObjective: To develop and validate a scoring system for colorectal neoplasia in Chinese opportunistic screening population,as well as evaluate its use with the fecal immunochemical test(FIT)in risk stratification for CRC screening.Methods: From November 2018 to April 2020,opportunistic screening population were enrolled form 23 hospitals nationwide in this prospective,multicenter study.All participants received the risk factor questionnaire,FIT and colonoscopy.Multiple logistic regression was applied to develop the scoring system.The predictive value of scoring system alone,FIT alone and scoring system combined with FIT were compared.Results: 1425 and 773 Chinese participants were enrolled to form the derivation and validation set,respectively.Multivariate analysis showed that five factors(age,gender,alcohol consumption,diabetes,and physical exercise)were significantly related to risk of colorectal neoplasia.We used these 5 factors to establish risk factors scoring system,which stratified the population into low-risk,medium-risk,and high-risk group.The area under the receiver operating characteristic curve of this scoring system was 0.67(95% CI:0.64-0.70).In the validation set,the prevalence of colorectal neoplasia in the low-risk,medium-risk,and high-risk group were 10.6%(95% CI: 7.8%-13.5%),24.6%(95% CI:18.3%-30.9%)and 30.2%(95% CI: 22.2%-38.3%),respectively.Compared with the low-risk group,prevalence of colorectal neoplasia in the medium-risk(OR: 2.7,95% CI:1.8-4.3)and the high-risk group(OR: 3.6,95% CI : 2.3-5.9)increased significantly.The sensitivity of high-risk-score alone for colorectal neoplasia,advanced neoplasia and CRC was 30.2%(95% CI:22.5%-39.1%),37.5%(95% CI:21.7%-56.3%)and 75.0%(95% CI:21.9%-98.7%),respectively.While for FIT alone,it was 11.1%(95% CI:6.4%-18.3%),31.3%(95% CI:16.7%-50.1%)and 75.0%(95% CI:21.9%-98.7%),respectively.When combined with FIT,the sensitivity of high-risk-score for colorectal neoplasia and advanced neoplasia increased to 35.7%(95% CI: 24.5%-44.8%)and 46.9%(95% CI: 29.5%-69.0%),while the sensitivity further increased to 65.1%(95% CI: 56.0%-73.2%)and 68.8%(95%CI: 49.9%-83.3%)when it came to medium-and-high-risk-score.Furthermore,the number need to screen(NNS)for a case of advanced neoplasia reduced from 23.6 to 10.1(high-risk-score combined with FIT)and 14.5(medium-and-high-risk-score combined with FIT),respectively.Conclusions: We developed and validated a colorectal neoplasia risk factor scoring system for Chinese population,which included age,gender,alcohol consumption,diabetes,and physical exercise.We also evaluated the predictive value of the scoring system combined with FIT for colorectal lesions.It turned that this strategy showed good sensitivity as well as high efficiency.Part II Predictive Value of Symptoms for Colorectal LesionsObjective: To determine the diagnostic accuracy of symptoms in predicting colorectal lesions in Chinese population.Methods: From November 2018 to April 2020,2381 Chinese participants were enrolled in this prospective and multicenter study.Examination indications and basic information of patients were recorded.Taking colonoscopy as gold standard,the diagnostic accuracy of symptoms in predicting colorectal lesions were evaluated with sensitivity,specificity,Youden index,positive predictive value(PPV),negative predictive value(NPV),positive likelihood ratio(+LR),negative likelihood ratio(-LR)and diagnostic odds ratio(DOR).Results: The average age of the participants was 49.08 year(SD=12.14)with 1266(53.2%)being male.1471(61.8%)participants underwent diagnostic colonoscopy and the most common examination indication was abdominal pain.Colorectal cancer(CRC)was detected in participants with only 4 kinds of symptoms,among which hematochezia had the highest sensitivity(45.0%,95% CI: 23.8%-68.0%).All symptoms had low PPV(<10%),among which only the PPV of hematochezia(8.7%,95% CI: 4.3%-16.2%)was over 5%.All symptoms had high NPV(>99%).Only hematochezia(11.18,95% CI: 6.63-18.87)had a +LR larger than 10,with others less than 2.Univariate analysis showed that hematochezia(DOR: 19.5,95% CI: 7.9-48.2,P <0.001,Fisher’s exact probability test)was associated with increased risk of CRC,which was still statistically significant after adjusted by risk stratification(adjusted DOR: 25.7,95% CI: 10.0-65.9;P<0.001).For advanced adenoma and non-advanced lesion,the sensitivity and PPV for all symptoms were low,with Youden index close to zero.Conclusions: Colonoscopy is warranted for patients with hematochezia due to increased risk of CRC,while other symptoms had little predictive value.With regard to advanced adenoma and non-advanced lesion,none of the symptoms had clear predictive value.Part Ⅲ Development of Colonoscopy and Cognition of Colonoscopists in China:A National SurveyObjective: To investigate the current situation of colonoscopy in China and the cognition of colonoscopists on related issues.Methods: The survey was conducted over the network targeted at gastroenterologists and colonoscopists from hospitals of different levels.Results: A total of 236 valid questionnaires were collected,involving 187 hospitals nationwide,143(76.5%)have an annual operation capacity of more than 5000 cases.In terms of bowel preparation,split-dosed PEG was most commonly used [113(60.4%)] and a total volume of 3 L PEG was the most adopted[126(67.4%)];verbal and written instructions was used more often than other methods in patient education;antifoaming agent was routinely used in 124(66.3%)hospitals.In terms of quality control,none of four quality control measures was implemented in more than 50% of the hospitals involved.In terms of polypectomy techniques,for lesions>1 cm,98% of the colonoscopists choose hot snare polypectomy or EMR,while the choices were divided when it comes to lesions<1 cm.Colonoscopists were inclined to recommend postpolypectomy colonoscopic surveillance more frequently than is recommended by practice guidelines.Conclusions: Our survey found several problems in the development of colonoscopy in China: the method of patient education of bowel preparation was simple;quality control still needs to be strengthened;polypectomy techniques and surveillance after polypectomy need to be further standardized.