Risk Of Colorectal Neoplasia After Negative Baseline Screening Colonoscopy

Colorectal cancer is one of the most familiar cancers in the world, whose morbidity isthe third of all cancers in the world and mortality is the second. In recent years, theincidence of colorectal cancer showed an increasing trend. Colonoscopy screening candetect cancer in the early stage and precancerous lesions, which related to timely treatment,so as to effectively reduce the morbidity and mortality of colorectal cancer.Colonoscopy screening interval of negative baseline screening colonoscopy crowdremains controversial. Foreign colorectal cancer screening guidelines recommended10years review interval for the initial negative colonoscopy crowd of asymptomaticaverage-risk population. Asymptomatic average-risk population are who have no colorectalcancer associated symptoms or warning signs, no colorectal cancer and colorectaladenomatous polyps medical history and family history, no hereditary colorectal cancerand inflammatory bowel disease history. The overseas screening guidelines recommended10years screening interval is based on the speculate average time of adenomatous polypsmalignant transformation, rather than the conclusions of the forward-looking results. Inaddition, even in the asymptomatic average risk population, the risk of colorectal canceroccurrence may be significantly difference due to different lifestyle, eating habits and otherrelevant factors. Therefore, the reasonable colonoscopy screening interval time of thenegative baseline colonoscopy crowd need to be further studied.This research in a retrospective survey based on27years colonoscopy check inChanghai Hospital, selected the negative baseline colonoscopy crowd and had bi-cohortstudy design. We obtained their consecutive colonoscopy reports and explore the risk ofcolorectal neoplasia occurred in different time intervals. The findings may play animportant role in making sure optimal colonoscopy screening time interval of Chinesepopulation colorectal cancer, and provide a preliminary basis for the development ofcolorectal cancer screening guidelines.Part1: Population analysis of initial colonoscopy Changhai HospitalAims: To analysis the population characteristics of population who received initialcolonoscopy in Changhai Hospital, select the negative baseline colonoscopy crowd, tolay the foundation for further study.Materials and Methods: Study population: Consecutive patients received firstcolonoscopy in Changhai Hospital, Second Military Medical University, from January1,1984to May16,2012, excluding the history of colonoscopy cases. Survey content and methods: Excerpts age, gender, and check time, visite reasons, diagnosis before checkand check conclusions from the colonoscopy database in hospital endoscopy centers.Statistical analysis: Descriptive analysis was performed to check reasons and diagnosticconclusions distribution of different gender, age, check time.Results: A total of99,956cases, men accounted for54.27%, and the40-60year oldsaccounted for50.18%. The proportion of the population who seek treatment because ofclinical symptoms was71.80%, while the asymptomatic physical examination populationis low (6.48%). The ratio of colorectal polyp/polypectomy, colorectal neoplasia checkaccounted for6.41%and5.30%respectively, which gradually increased with age. In thecrowd, female was significantly less than men (5.34%vs.7.34%,4.70%vs.5.82%).Diagnosises were normal in58,439cases (58.46%), polyps lesion26,358cases (26.37%),8324cases of colorectal neoplasia (8.33%). In recent years, the proportion of diagnosis ofcolorectal neoplasia increased apparently. The incidence of colorectal neoplasia in eldgroup was significantly higher than the younger group. and the female was significantlyless than men (20.77%vs31.08%,7.08%vs9.38%).Conclusions: The patients received first colonoscopy in Changhai Hospital, theproportion of males is higher than females, and most of the population are40-60yearsold. Major check reasons is clinical symptoms; most of the results is negative, followedby polyp lesions. In recent years, the proportion of colorectal neoplasia in the diagnosisshows upward trend.Part2: Risk of colorectal neoplasia after negative baseline screeningcolonoscopyAims: To review the following colonoscopy of negative baseling screening colonoscopycrowd, and explore colorectal neoplasia morbidity at different time intervals in differentgender, age and risk level.Materials and Methods: Study population: Based on the first part of the study, we selectthe asymptomatic average-risk populations with negative baseling screening colonoscopybetween January1,1995to December31,2005as the research object. Asymptomaticaverage-risk population are who have no colorectal cancer associated symptoms orwarning signs, no colorectal cancer and colorectal adenomatous polyps medical historyand family history, no hereditary colorectal cancer and inflammatory bowel diseasehistory. Survey content and methods: With bi-cohort study design, we designed questionnaire and followed crowd by telephone. The survey contents included all thefollowing colonoscopy. The risk stratification factors of colorectal cancer (Our researchgroup established the risk scoring system of the colorectal advanced neoplasia inaverage-risk population and the system include age, gender, smoking status, history ofdiabetes, green vegetables intake, pickled food intake, the fried smoked food intake,white meat intake and other factors). The definition of proximal and distal colon: theproximal colon is from the cecum to the splenic flexure of the colon, including the cecum,ascending colon, hepatic flexure, transverse colon and splenic flexure; distal colon isfrom the descending colon to the rectum, including the descending colon, sigmoid, thejunction of sigmoid and rectum, and rectum. Statistical analysis:（1） Calculate all theresearch object risk score according to the risk scoring system of the colorectal advancedneoplasia in average-risk population mentioned above. The population is divided intolow-risk group (≤3) and high-risk group (>3).（2）Use the life table survival analysismethod study to caculate total cumulative risk of colorectal neoplasia (polyps, adenomas,advanced neoplasia) and cumulative risks of different gender, ages, risk level populationsoccur colorectal neoplasia.（3）Foreign studies have shown that the28.7%of polypscumulative incidence and5%of advanced tumors cumulative incidence were consideredsafe when estimated the colonoscopy screening interval.Results: We recruited455cases. The average age is54.05±8.97years old,175cases aremale (38.46%),280cases are female (61.54%). The incidence of colorectal polyps is20%, colorectal adenoma is5.27%, colorectal advanced adenomas is1.99%, andcolorectal invasive carcinoma is0.66%. The proportion of proximal colon lesions is28.57%(26/91), the distal colon lesions is57.14%(52/91), the proximal and distal colonlesions is14.29%(13/91). The incidence of polyps in male cases (26.86%) issignificantly higher than that in female cases(15.71%)(P=0.004). The difference ofpolyps anatomical distribution in different gender is statistically significant (P=0.014).The incidence of polyps in≥60years group (24.53%) was significantly higher than in<60years group (18.62%)(P=0.183). The distribution of polyps in different age is notsignificantly different (P=0.075). Adenomas anatomical distribution was not significantlydifferent in different gender and age (P>0.05).A total of454cases are included in the survival analysis (1missing),280cases arefemale and174cases are male.91patients had polyps lesions. The cumulative incidenceof polyps during5years,8years and10years are11.9%,25.3%(28.7%),41.6%.5years, 10years, more than12years the cumulative incidence of colorectal adenoma are4.2%,8.5%and21%.5years,12years, more than12years, the cumulative incidence ofcolorectal advanced neoplasia are2%,3.9%(<5%) and14.6%. For men5years,10yearscumulative incidence of polyps were20.5%and45.1%, higher than female population(6.5%,39.5%), For men5years polyps cumulative incidence rate (25.6%) was equivalentto9years cumulative incidence of female (25.4%). In≥60years group,5years,10yearscumulative incidence of polyps were16.7%,47.1%, higher than the10.7%,39.4%in <60years group. In≥60years group6years polyps cumulative incidence rate (24.5%) wassimilar with9years polyp cumulative incidence of <60years group (25%). In thehigh-risk group (>3),5-year,10years cumulative incidence of polyps (16.6%,47.2%),higher than the low-risk group population (≤3points)(9.1%,43.1%). High risk grouppopulations7years polyps cumulative incidence (28.6%) was similar with9years polypscumulative incidence of the low risk group (25.1%).Conclusions: In the negative baseline screening colonoscopy crowd,5years cumulativeincidence of colorectal polyps, adenomas, advanced neoplasia are low. A lower risk ofpolyps lesions occurred in8years and advanced neoplasia in12years. To polyps,5yearsand10years cumulative incidence of colorectal polyps in male group is higher thanfemale; A lower risk of polyps lesions occurred at6years,9years in Male and femalepopulation respectively. Cumulative incidence of polyp in the population aged≥60yearsis higher than people aged <60years. A lower risk of polyps lesions occurred at6years,9years in the population aged≥60years and aged <60years respectively. In low-riskgroup populations (≤3),5years and10year cumulative incidence of colorectal polypsare significantly lower than the high-risk group populations (>3). A lower risk of polypslesions occurred at9years,7years in low-risk group and high-risk group populationrespectively.