***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 
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    Input: BACKGROUND We tested the hypothesis that dietary intervention can inhibit the development of recurrent colorectal adenomas , which are precursors of most large-bowel cancers . METHODS We r and omly assigned 2079 men and women who were 35 years of age or older and who had had one or more histologically confirmed colorectal adenomas removed within six months before r and omization to one of two groups : an intervention group given intensive counseling and assigned to follow a diet that was low in fat ( 20 percent of total calories ) and high in fiber ( 18 g of dietary fiber per 1000 kcal ) and fruits and vegetables ( 3.5 servings per 1000 kcal ) , and a control group given a st and ard brochure on healthy eating and assigned to follow their usual diet . Subjects entered the study after undergoing complete colonoscopy and removal of adenomatous polyps ; they remained in the study for approximately four years , undergoing colonoscopy one and four years after r and omization . RESULTS A total of 1905 of the r and omized subjects ( 91.6 percent ) completed the study . Of the 958 subjects in the intervention group and the 947 in the control group who completed the study , 39.7 percent and 39.5 percent , respectively , had at least one recurrent adenoma ; the unadjusted risk ratio was 1.00 ( 95 percent confidence interval , 0.90 to 1.12 ) . Among subjects with recurrent adenomas , the mean ( + /-SE ) number of such lesions was 1.85+/-0.08 in the intervention group and 1.84+/-0.07 in the control group . The rate of recurrence of large adenomas ( with a maximal diameter of at least 1 cm ) and advanced adenomas ( defined as lesions that had a maximal diameter of at least 1 cm or at least 25 percent villous elements or evidence of high- grade dysplasia , including carcinoma ) did not differ significantly between the two groups . CONCLUSIONS Adopting a diet that is low in fat and high in fiber , fruits , and vegetables does not influence the risk of recurrence of colorectal adenomas Recent evidence suggests that resistant starch ( RS ) is the single most important substrate for bacterial carbohydrate fermentation in the human colon . During two 4-wk periods . 12 healthy volunteers consumed a controlled basal diet enriched with either amylomaize starch ( 55.2 + /- 3.5 g RS/d ; high-RS diet ) or available cornstarch ( 7.7 + /- 0.3 g RS/d ; low-RS diet ) . Approximately 90 % of the RS consumed disappeared during intestinal passage ; increased fermentation was verified by elevated breath-hydrogen excretion . During the high-RS diet , fecal wet and dry weight increased 49 % and 56 % , respectively ( P < or = 0.005 ) , whereas stool water content did not change significantly . Fecal concentrations and daily excretion of short-chain fatty acids were not different in the two study periods . During the high-RS diet , bacterial beta-glucosidase activity decreased by 26 % ( P < or = 0.05 ) . Fecal concentrations of total and secondary bile acids were significantly lower during the high-RS than during the low-RS period [ a decrease of 30 % ( P < or = 0.05 ) and 32 % ( P < or = 0.01 ) , respectively , in total and secondary bile acids ] whereas concentrations of primary bile acids were unaffected by RS consumption . During the high-RS diet , fecal concentrations of total neutral sterols decreased by 30 % ( P < or = 0.005 ) and fecal concentrations of 4-cholesten-3-one decreased by 36 % ( P < or = 0.05 ) . These data suggest that RS has potentially important effects on bacterial metabolism in the human colon that may be relevant for cancer prevention BACKGROUND The identification and removal of adenomatous polyps and post-polypectomy surveillance are considered to be important for the control of colorectal cancer . In current practice , the intervals between colonoscopies after polypectomy are variable , often a year long , and not based on data from r and omized clinical trials . We sought to determine whether follow-up colonoscopy at three years would detect important colonic lesions as well as follow-up colonoscopy at both one and three years . METHODS Patients were eligible if they had one or more adenomas , no previous polypectomy , and a complete colonoscopy and all their polyps had been removed . They were r and omly assigned to have follow-up colonoscopy at one and three years or at three years only . The two study end points were the detection of any adenoma , and the detection of adenomas with advanced pathological features ( defined as those > 1 cm in diameter and those with high- grade dysplasia or invasive cancer ) . RESULTS Of 2632 eligible patients , 1418 were r and omly assigned to the two follow-up groups , 699 to the two-examination group and 719 to the one-examination group . The percentage of patients with adenomas in the group examined at one and three years was 41.7 percent , as compared with 32.0 percent in the group examined at three years ( P = 0.006 ) . The percentage of patients with adenomas with advanced pathological features was the same in both groups ( 3.3 percent ) . CONCLUSIONS Colonoscopy performed three years after colonoscopic removal of adenomatous polyps detects important colonic lesions as effectively as follow-up colonoscopy after both one and three years . An interval of at least three years is recommended before follow-up colonoscopy after both one and three years . An interval of at least three years is recommended before follow-up examination after colonoscopic removal of newly diagnosed adenomatous polyps . Adoption of this recommendation nationally should reduce the cost of post-polypectomy surveillance and screening After polypectomy for adenomatous colorectal polyps , 201 persons were r and omized to receive counselling on a diet low in fat ( the lesser of 50 g/day or 20 % of energy ) and high in fibre ( 50 g/day ) ( LFHF ) , or to follow a normal western diet ( ND ) , high in fat and low in fibre . After 12 months of counselling , fat consumption was about 25 % of energy in the LFHF group and 33 % in the ND group ; fibre consumption was 35 g and 16 g respectively . After an average of two years of follow-up , an intention to treat analysis led to a ratio of cumulative incidence rates of 1.2 ( 95 % CL 0.6 - 2.2 ) for recurrence of neoplastic polyps , a finding which suggests no significant difference between dietary groups over the period of observation . An exploratory analysis conducted among 142 persons with substantial diet counselling indicated a reduced risk of neoplastic polyp recurrence in women ( RR = 0.5 ) , associated with reduced concentrations of faecal bile acids while on the LFHF diet , but indicated an increased risk of recurrence in men ( RR = 2.1 ) , associated with increased faecal bile acids . Although a larger study would be needed to rule out the role of chance , these findings of gender-specific associations between diet counselling and both faecal bile acid concentrations and recurrence of colorectal neoplasia are consistent with recently published evidence of differences between genders We established a protocol for an interventional r and omized controlled trial for prevention of colorectal cancer by attaching special importance to feasibility . The subjects were patients with multiple colorectal tumors . Two regimens were formulated for prevention of colorectal cancer . One was dietary guidance alone ( Regimen I ) , and the other was dietary guidance plus eating wheat bran biscuits ( Regimen II ) . The main end points of the trial were examinations for recurrence of colorectal tumors after 2 and 4 years . The target number of patients was 200 in total , i.e. 100 for each group . During the 18 months from the beginning of recruiting of subjects ( up to November 1994 ) , 28 ( 97 % ) of the 29 patients recruited for Regimen I and 32 ( 97 % ) of the 33 patients recruited for Regimen II agreed to participate in the trial . The trial is progressing well BACKGROUND Several recent large prospect i ve cohort studies have failed to demonstrate the presumed protective effect of fruit , vegetable , and dietary fiber consumption on colorectal cancer risk . To further explore this issue , we have examined these associations in a population that consumes relatively low amounts of fruit and vegetables and high amounts of cereals .  METHODS We examined data obtained from a food-frequency question naire used in a population -based prospect i ve mammography screening study of women in central Sweden . Women with colorectal cancer diagnosed through December 31 , 1998 , were identified by linkage to regional cancer registries . Cox proportional hazards models were used to estimate relative risks . All statistical tests were two-sided . RESULTS During an average 9.6 years of follow-up of 61 463 women , we observed 460 incident cases of colorectal cancer ( 291 colon cancers , 159 rectal cancers , and 10 cancers at both sites ) . In the entire study population , total fruit and vegetable consumption was inversely associated with colorectal cancer risk . Subanalyses showed that this association was due largely to fruit consumption . The association was stronger , however , and the dose-response effect was more evident among individuals who consumed the lowest amounts of fruit and vegetables . Individuals who consumed less than 1.5 servings of fruit and vegetables per day had a relative risk for developing colorectal cancer of 1.65 ( 95 % confidence interval = 1.23 to 2.20 ; P(trend ) = .001 ) compared with individuals who consumed more than 2.5 servings . We observed no association between colorectal cancer risk and the consumption of cereal fiber , even at amounts substantially greater than previously examined , or of non-cereal fiber . CONCLUSIONS Individuals who consume very low amounts of fruit and vegetables have the greatest risk of colorectal cancer . Relatively high consumption of cereal fiber does not appear to lower the risk of colorectal cancer BACKGROUND Recent studies suggest that long-term cigarette smoking is associated with an increased risk of colorectal cancer .  Whether the association is causal or due to confounding remains unclear . METHODS We examined cigarette smoking in relation to  colorectal cancer mortality , evaluating smoking duration and recency and controlling for potential confounders in the Cancer Prevention Study II . This prospect i ve nationwide mortality study of 1 184 657 adults ( age > or = 30 years ) was begun by the American Cancer Society in 1982 . After exclusions , our analytic cohort included 312 332 men and 469 019 women , among whom 4432 colon or rectal cancer deaths occurred between 1982 and 1996 among individuals who were cancer free in 1982 .  Rate ratios ( RRs ) and 95 % confidence intervals ( CIs ) were estimated by fitting Cox proportional hazards models . All statistical tests were two-sided . RESULTS Multivariate-adjusted colorectal cancer mortality rates were highest among current smokers , were intermediate among former smokers , and were lowest in lifelong nonsmokers . The multivariate-adjusted RR ( 95 % CI ) for current compared with never smokers was 1.32 ( 1.16 - 1.49 ) among men and 1.41 ( 1.26 - 1.58 ) among women . Increased risk was evident after 20 or more years of smoking for men and women combined as compared with never smokers . Risk among current and former smokers increased with duration of smoking and average number of cigarettes smoked per day ; risk in former smokers decreased significantly with years since quitting . If the multivariate-adjusted RR estimates in this study do , in fact , reflect causality , then approximately 12 % of colorectal cancer deaths among both men and women in the general U.S. population in 1997 were attributable to smoking . CONCLUSIONS Long-term cigarette smoking is associated with increased risk of colorectal cancer mortality in both men and women . Clear reduction in risk is observed with early smoking cessation BACKGROUND Frequent consumption of fruit and vegetables has been associated with a reduced risk of  colorectal cancer  in many observational studies . METHODS We prospect ively investigated the association between fruit and vegetable consumption and the incidence of colon and rectal cancers in two large cohorts : the Nurses ' Health Study ( 88 764 women ) and the Health Professionals ' Follow-up Study ( 47 325 men ) . Diet was assessed and cumulatively up date d in 1980 , 1984 , 1986 , and 1990 among women and in 1986 and 1990 among men . The incidence of cancer of the colon and rectum was ascertained up to June or January of 1996 , respectively . Relative risk ( RR ) estimates were calculated with the use of pooled logistic regression models accounting for various potential confounders . All statistical tests were two-sided . RESULTS With a follow-up including 1 743 645 person-years and 937 cases of colon cancer , we found little association of colon cancer incidence with fruit and vegetable consumption . For women and 
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REVIEW ER 'S CONCLUSIONS There is currently no evidence from RCTs to suggest that increased dietary fibre intake will reduce the incidence or recurrence of adenomatous polyps within a two to four year period