***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: Dietary calcium may inhibit colonic carcinogenesis promoted by high fat , phosphate , and low fibre diets . In persons at risk for colon cancer oral calcium supplements significantly suppress increased rectal epithelial proliferation . This was studied in a cohort of 35 volunteers : 26 first degree relatives of colorectal cancer patients and nine who had had colonic adenomas ( mean age 51.6 years , 17 ( 49 % ) men , all negative for large bowel neoplasia ) . 1.25 - 1.5 g elemental calcium was given in divided daily doses for three months . Rectal pinch biopsies were taken without bowel preparation , before and mean 8.4 weeks during and 7.2 weeks after treatment and incubated with tritiated thymidine . The mean number of labelled cells , as a ratio of the total number of crypt cells ( labelling index-LI ) , and their crypt position , were determined . The mean number of labelled cells decreased during treatment by 29 % , especially in the basal three-fifths of crypts . There was also a significant 10 % increase in mean number of crypt cells during treatment . [ Mean LI decreased by 36 % ( p less than 0.001 ) during calcium treatment and almost returned to basal values after cessation . ] If a raised LI is a marker of potential malignancy and a r and omised clinical trial confirms that calcium suppresses it , dietary intervention studies in high risk persons are indicated The Polyp Prevention Trial ( PPT ) was a multicenter r and omized clinical trial design ed to determine the effects of a high-fiber , high-fruit and vegetable , low-fat diet on the recurrence of adenomatous polyps in the large bowel . Detailed dietary intake and supplement use data were collected at baseline and at each of 4 annual study visits . Adenoma recurrence was ascertained by complete colonoscopy at baseline and after 1 and 4 y. Recurrence was found in 754 of the 1905 trial participants . We evaluated the association between calcium and vitamin D intake and adenomatous polyp recurrence after adjusting for intervention group , age , gender , nonsteroidal anti-inflammatory drug use , total energy intake , and the interaction of gender and intervention group . Vitamin D models were also adjusted for the location of the clinic site . Dietary variables were adjusted for total energy intake via the residual method . There were no overall significant associations between adenoma recurrence and dietary calcium intake [ odds ratio ( OR ) for the 5th compared with the lowest quintile = 0.91 ; 95 % CI = 0.67 - 1.23 ; P-trend = 0.68 ] , total calcium intake ( OR = 0.86 ; 95 % CI = 0.62 - 1.18 ; P-trend = 0.20 ) , or  dietary vitamin D intake ( OR = 0.93 ; 95 % CI = 0.69 - 1.25 ; P-trend = 0.43 ) averaged over follow-up . Total vitamin D intake was weakly inversely associated with adenoma recurrence ( OR = 0.84 ; 95 % CI = 0.62 - 1.13 ; P-trend = 0.03 ) . Supplemental calcium and vitamin D use during follow-up also were inversely associated with adenoma recurrence ( OR for any compared with no use = 0.82 ; 95 % CI = 0.68 - 0.99 ; and OR = 0.82 ; 95 % CI = 0.68 - 0.99 ; for calcium and vitamin D , respectively ) . Slightly stronger associations were noted for the prevention of multiple recurrences . Our analyses did not suggest a significant effect modification between total calcium and total vitamin D intake ( P = 0.14 ) on risk for adenoma recurrence . This trial cohort provides some evidence that calcium and vitamin D may be inversely associated with adenoma recurrence BACKGROUND Recent epidemiologic studies have generally reported a modest inverse association between calcium intake and the risk of colorectal cancer . However , findings pertaining to specific subsites in the colorectum have been conflicting . OBJECTIVE Our objective was to prospect ively examine the relations between intakes of calcium and dairy foods and the risk of colorectal cancer , overall and by anatomic subsite , in men from the Cohort of Swedish Men . DESIGN In 1997 , 45 306 men aged 45 - 79 y and without a history of cancer completed a food-frequency question naire .  The men were followed through 31 December 2004 . RESULTS During a mean follow-up of 6.7 y , we ascertained 449 incident cases of colorectal cancer . After adjustment for age and other known or potential risk factors , the multivariate rate ratio ( RR ) of colorectal cancer for men in the highest quartile of total calcium intake compared with those in the lowest quartile was 0.68 ( 95 % CI : 0.51 , 0.91 ; P for trend = 0.01 ) . A high consumption of dairy foods was also associated with a lower risk of colorectal cancer . The multivariate RR of colorectal cancer for > or = 7 servings/d of total dairy foods compared with < 2 servings/d was 0.46 ( 0.30 , 0.71 ; P for trend = 0.01 ) . For cancer subsites , the corresponding RRs were 0.37 ( 0.16 , 0.88 ) for proximal colon , 0.43 ( 0.20 , 0.93 ) for distal colon , and 0.48 ( 0.23 , 0.99 ) for rectum . CONCLUSION Our findings provide support for inverse associations between intakes of calcium and dairy foods and the risk of colorectal cancer Although rectal mucosal labeling index is thought to be a useful surrogate biomarker for colorectal cancer , the ability of the index to predict future neoplasia is unclear . We obtained  rectal mucosal biopsies from 333 participants of a r and omized controlled chemoprevention trial of calcium supplementation  to determine whether labeling index was correlated with concurrent or future colorectal neoplasms . Labeling index was measured using proliferating cell nuclear antigen immunohistochemistry . Adenomas were enumerated at the time of the biopsies ( cross-sectional ) and 3 years later ( prospect i ve ) . We used logistic regression to test for an association of adenoma occurrence with overall labeling index , the mean proliferative height , and labeling index in the upper 40 % of colon crypts . In the cross-sectional analysis , we found indications that higher proliferation was associated with an increase in the prevalence of adenomas . The overall adjusted odds ratios ( OR ) ( 95 % confidence interval ) were 1.14 ( 0.90 - 1.45 ) per % crypt labeling index , OR 1.08 ( 0.99 - 1.19 ) for upper crypt proliferation , and OR 1.07 ( 1.03 - 1.12 ) for proliferative height . In contrast , individuals with higher labeling index at baseline were actually less likely to have adenomas in the prospect i ve analyses : OR 0.80 ( 0.62 - 1.02 ) per % crypt labeling index , OR 0.86 ( 0.73 - 1.00 ) for upper crypt index , and OR 0.97 ( 0.93 - 1.01 ) for proliferative height . Proliferative index does not predict future colorectal neoplasia , although it may be weakly associated with the presence of current adenomas . These results have important implication s for the design of future intervention studies . Although it may be attractive to include the measurement of intermediate markers in large controlled trials , until we have more confidence in their performance , we should rely on better proven and more reliable intermediates , such as adenomas The Women 's Health Initiative ( WHI ) is a large and complex clinical investigation of strategies for the prevention and control of some of the most common causes of morbidity and mortality among postmenopausal women , including cancer , cardiovascular disease , and osteoporotic fractures . The WHI was initiated in 1992 , with a planned completion date of 2007 . Postmenopausal women ranging in age from 50 to 79 are enrolled at one of 40 WHI clinical centers nationwide into either a clinical trial ( CT ) that will include about 64,500 women or an observational study ( OS ) that will include about 100,000 women . The CT is design ed to allow r and omized controlled evaluation of three distinct interventions : a low-fat eating pattern , hypothesized to prevent breast cancer and colorectal cancer and , secondarily , coronary heart disease ; hormone replacement therapy , hypothesized to reduce the risk of coronary heart disease and other cardiovascular diseases and , secondarily , to reduce the risk of hip and other fractures , with increased breast cancer risk as a possible adverse outcome ; and calcium and vitamin D supplementation , hypothesized to prevent hip fractures and , secondarily , other fractures and colorectal cancer . Overall benefit-versus-risk assessment is a central focus in each of the three CT components . Women are screened for participation in one or both of the components -- dietary modification ( DM ) or hormone replacement therapy (HRT)--of the CT , which will r and omize 48,000 and 27,500 women , respectively . Women who prove to be ineligible for , or who are unwilling to enroll in , these CT components are invited to enroll in the OS . At their 1-year anniversary of r and omization , CT women are invited to be further r and omized into the calcium and vitamin D ( CaD ) trial component , which is projected to include 45,000 women . The average follow-up for women in either CT or OS is approximately 9 years . Concerted efforts are made to enroll women of racial and ethnic minority groups , with a target of 20 % of overall enrollment in both the CT and OS . This article gives a brief description of the rationale for the interventions being studied in each of the CT components and for the inclusion of the OS component . Some detail is provided on specific study design choices , including eligibility criteria , recruitment strategy , and sample size , with attention to the partial factorial design of the CT . Some aspects of the CT monitoring approach are also outlined . The scientific and logistic complexity of the WHI implies particular leadership and management challenges . The WHI organization and committee structure employed to respond to these challenges is also briefly described A protective effect of calcium and /or dairy products on  colorectal cancer  has been reported in epidemiological studies but the findings are considered inconsistent . In particular , it is unclear whether they act at a particular step of the adenoma‐carcinoma sequence . To investigate the effect of dairy product consumption and dietary calcium , vitamin D and phosphorus intake on the adenoma‐carcinoma sequence in the French E3N‐EPIC prospect i ve study . The population for the study of risk factors for adenomas was composed of 516 adenoma cases , including 175 high‐risk adenomas , and of 4,804 polyp‐free subjects confirmed by colonoscopy . The population for the colorectal cancer study was composed of 172 cases and 67,312 cancer‐free subjects .  Diet was assessed using a self‐administered question naire completed at baseline . There was a trend of decreasing risk of both adenoma ( ptrend= 0.04 ) and cancer ( ptrend=0.08 ) with increasing calcium intake , with RRs for adenoma and cancer of 0.80 ( IC 95%=0.62–1.03 ) and 0.72 ( 95 % CI=0.47–1.10 ) , respectively , in the fourth quartile compared to the first . A protective effect of dairy products on adenoma ( RRQ4 vs. Q1= 0.80 , 95 % CI=0.62‐1.05 , ptrend= 0.04 ) was observed and of milk consumption on colorectal cancer ( RRQ4vs . Q1= 0.54 , 95 % CI=0.33–0.89 , ptrend= 0.09 ) , although the latter did not reach significance . Phosphorus  intake also decreased the risk of adenoma ( RRQ4 vs. Q1=0.70 , 95 % CI=0.54–0.90 , ptrend= 0.005 ) .  No vitamin D effect was identified . Our data support the hypothesis that calcium , dairy products and phosphorus exert a protective effect at certain steps of the adenoma‐carcinoma sequence . © 2005 Wiley‐Liss , BACKGROUND AND METHODS Laboratory , clinical , and epidemiologic evidence suggests that calcium may help prevent colorectal adenomas . We conducted a r and omized , double-blind trial of the effect of supplementation with calcium carbonate on the recurrence of colorectal adenomas . We r and omly assigned 930 subjects ( mean age , 61 years ; 72 percent men ) with a recent history of colorectal adenomas to receive either calcium carbonate ( 3 g [ 1200 mg of elemental calcium ] daily ) or placebo , with follow-up colonoscopies one and four years after the qualifying examination . The primary end point was the proportion of subjects in whom at least one adenoma was detected after the first follow-up endoscopy but up to ( and including ) the second follow-up examination . Risk ratios for the recurrence of adenomas were adjusted for age , sex , 
    Output:
    
Although the evidence from two RCTs suggests that calcium supplementation might contribute to a moderate degree to the prevention of colorectal adenomatous polyps , this does not constitute sufficient evidence to recommend the general use of calcium supplements to prevent colorectal cancer