***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND / AIMS The frequency of colorectal adenomas , the precursor lesions for most cases of colorectal carcinoma , has been generally measured as prevalence rates of adenomas at autopsy or colonoscopy . The aim of this study was to estimate the incidence rate of adenomas and compare it with the adenoma recurrence rate . METHODS Data on colonoscopies performed in three New York City practice s were collected prospect ively . The cumulative rate of adenoma diagnosis on repeat colonoscopy was calculated for patients with no abnormalities on index colonoscopy  ( " incidence " rate ) and for patients with adenomas on the index colonoscopy ( " recurrence " rate ) . RESULTS The cumulative incidence rate of adenomas at 36 months was 16 % , and the cumulative recurrence rate at 36 months was 42 % ( P < 0.004 ) . The recurrence rate was higher in patients with multiple adenomas than in those with a single adenoma on index colonoscopy , although the increase was not statistically significant . CONCLUSIONS Although the recurrence rate has always been assumed to be elevated , this study is the first to compare the recurrence rate of adenomas with the incidence rate directly and to show that the recurrence rate is indeed elevated The National Polyp Study ( NPS ) , a r and omized clinical trial to evaluate effective surveillance of patients discovered to have one or more colorectal adenomas , was the framework for this statistical analysis which used a multiple logistic model to assess the independent risk factors of patient and polyp characteristics associated with high- grade dysplasia in adenomas . The data base included 3371 adenomas from 1867 patients . Adenoma size and the extent of the villous component were found to be the major independent polyp risk factors associated with high- grade dysplasia ( p less than 0.0001 ) . The adjusted odds ratios were 3.3 for medium-sized adenomas and 7.7 for large adenomas relative to small adenomas and 2.7 for villous A adenomas , 3.4 for villous B adenomas , and 8.1 for villous C and D adenomas relative to tubular adenomas . Increased frequency of high- grade dysplasia in adenomas located distal to the splenic flexure was attributable mainly to increased size and villous component rather than to location per se . The adjusted odds ratio was 1.4 ( p less than 0.11 ) for left-sided location . Multiplicity of adenomas affected the risk for high- grade dysplasia in patients but was dependent on adenoma size and villous component and was not an independent factor . The adjusted odds ratio was 1.3 ( p less than 0.17 ) for multiplicity . Increasing age was associated with risk for high- grade dysplasia in patients , and this effect was independent of the effect of adenoma size and histological type . The adjusted odds ratio was 1.8 ( p less than 0.0016 ) for age greater than or equal to 60 yr . Gender was not associated with high- grade dysplasia . The adjusted odds ratio was 1.0 ( p less than 0.95 ) for men . The size of the patient series , the prospect i ve nature of the data collection , the completeness of information on all patients , the requirements of complete examination of the entire colon and pathological examination of all lesions encountered , and the exclusion of patients with previously diagnosed adenomas are , collectively , features unique to this study . The detailed model provided by the analysis integrates multiple patient and adenoma factors associated with high- grade dysplasia in colorectal adenomas BACKGROUND & AIMS Outcomes of colon surveillance after colorectal cancer screening with colonoscopy are uncertain . We conducted a prospect i ve study to measure incidence of advanced neoplasia in patients within 5.5 years of screening colonoscopy .  METHODS Three thous and one hundred twenty-one asymptomatic subjects , age 50 to 75 years , had screening colonoscopy between 1994 and 1997 in the Department of Veterans Affairs . One thous and one hundred seventy-one subjects with neoplasia and 501 neoplasia-free controls were assigned to colonoscopic surveillance over 5 years . Cohorts were defined by baseline findings . Relative risks for advanced neoplasia within 5.5 years were calculated . Advanced neoplasia was defined as tubular adenoma greater than > or = 10 mm , adenoma with villous histology , adenoma with high- grade dysplasia , or invasive cancer . RESULTS Eight hundred ninety-five ( 76.4 % ) patients with neoplasia and 298 subjects ( 59.5 % ) without neoplasia at baseline had colonoscopy within 5.5 years ; 2.4 % of patients with no neoplasia had interval advanced neoplasia . The relative risk in patients with baseline neoplasia was 1.92 ( 95 % CI : 0.83 - 4.42 ) with 1 or 2 tubular adenomas < 10 mm , 5.01 ( 95 % CI : 2.10 - 11.96 ) with 3 or more tubular adenomas < 10 mm , 6.40 ( 95 % CI : 2.74 - 14.94 ) with tubular adenoma > or = 10 mm , 6.05 ( 95 % CI : 2.48 - 14.71 ) for villous adenoma , and 6.87 ( 95 % CI : 2.61 - 18.07 ) for adenoma with high- grade dysplasia . CONCLUSIONS There is a strong association between results of baseline screening colonoscopy and rate of serious incident lesions during 5.5 years of surveillance . Patients with 1 or 2 tubular adenomas less than 10 mm represent a low-risk group compared with other patients with colon neoplasia 
    Output:
    
6 Gimeno-Garcı́a AZ , Ramı́rez F , Gonzalo V , Belaguer F , Petit A , Pellisé M , Llach J , Bordas JM , Piqué JM , Castells A. High- grade dysplasia as a risk factor of metachronous advanced neoplasms in patients with advanced adenomas .
Ongoing colorectal cancer risk despite surveillance colonoscopy : the Polyp Prevention Trial Continued Follow-up Study .