***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: Several lines of evidence suggest that vitamin D may reduce incidence of breast cancer , but few epidemiologic studies have addressed the relation of plasma vitamin D metabolites to the risk of this disease . We prospect ively examined the relationship between plasma levels of 25-hydroxyvitamin D [ 25(OH)D ] and 1,25-dihydroxyvitamin D [ 1,25(OH)2D ] and  risk of breast cancer  in a case-control study nested within the Nurses ' Health Study cohort .  Blood sample s were collected from study participants in 1989 - 1990 . Breast cancer cases developing between blood collection and June 1 , 1996 , were matched to cancer-free controls on the basis of age , menopausal status , and other factors . Stored plasma sample s from 701 cases and 724 controls were available for metabolite analysis . Cases had a lower mean 25(OH)D level than controls ( P = 0.01 ) , but mean 1,25(OH)2D levels were similar ( P = 0.49 ) . High levels of both metabolites were associated with a nonsignificant lower risk of breast cancer . Women in the highest quintile of 25(OH)D had a relative risk of 0.73 ( 95 % confidence interval = 0.49 - 1.07 ; Ptrend = 0.06 ) compared with those in the lowest quintile . For 1,25(OH)2D , the comparable relative risk was 0.76 ( 95 % confidence interval = 0.52 - 1.11 ; Ptrend = 0.39 ) . For both metabolites , the association was stronger in women ages 60 years and older , but results were not statistically significant . Our findings suggest that high levels of 25(OH)D , and perhaps 1,25(OH)2D , may be modestly associated with reduced risk of breast cancer We investigated the association between plasma 25(OH)D and the subsequent  colorectal cancer incidence risk by a nested case – control study in The Japan Public Health Center-based Prospect i ve Study , covering 375 newly diagnosed cases of colorectal cancer from 38 373 study subjects during a 11.5-year follow-up after blood collection . Two controls were matched per case on sex , age , study area , date of blood draw , and fasting time . In a conditional logistic regression model with matched pairs adjusted for smoking , alcohol consumption , body mass index , physical exercise , vitamin supplement use , and family history of colorectal cancer , plasma 25(OH)D was not significantly associated with colorectal cancer in men or in women . However , the lowest category of plasma 25(OH)D was associated with an elevated risk of rectal cancer in both men ( odds ratio ( OR ) , 4.6 ; 95 % confidence interval ( CI ) , 1.0–20 ) and women ( OR , 2.7 , 95 % CI , 0.94–7.6 ) , compared with the combined category of the other quartiles . Our results suggest that a low level of plasma 25(OH)D may increase the risk of rectal cancer BACKGROUND Numerous observational studies have found supplemental calcium and vitamin D to be associated with reduced risk of common cancers . However , interventional studies to test this effect are lacking . OBJECTIVE The purpose of this analysis was to determine the efficacy of calcium alone and calcium plus vitamin D in reducing incident cancer risk  of all types . DESIGN This was a 4-y , population -based , double-blind , r and omized placebo-controlled trial . The primary outcome was fracture incidence , and the principal secondary outcome was cancer incidence . The subjects were 1179 community-dwelling women r and omly selected from the population of healthy postmenopausal women aged > 55 y in a 9-county rural area of Nebraska centered at latitude 41.4 degrees N. Subjects were r and omly assigned to receive 1400 - 1500 mg supplemental calcium/d alone ( Ca-only ) , supplemental calcium plus 1100 IU vitamin D3/d ( Ca + D ) , or placebo . RESULTS When analyzed by intention to treat , cancer incidence was lower in the Ca + D women than in the placebo control subjects ( P < 0.03 ) . With the use of logistic regression , the unadjusted relative risks ( RR ) of incident cancer in the Ca + D and Ca-only groups were 0.402 ( P = 0.01 ) and 0.532 ( P = 0.06 ) , respectively . When analysis was confined to cancers diagnosed after the first 12 mo , RR for the Ca + D group fell to 0.232 ( CI : 0.09 , 0.60 ; P < 0.005 ) but did not change significantly for the Ca-only group . In multiple logistic regression models , both treatment and serum 25-hydroxyvitamin D concentrations were significant , independent predictors of cancer risk . CONCLUSIONS Improving calcium and vitamin D nutritional status substantially reduces  all-cancer risk in postmenopausal women . This trial was registered at clinical trials.gov as NCT00352170 Abstract Objective : The hormone 1,25-dihydroxyvitamin D ( 1,25(OH)2D ) promotes prostate epithelial cell differentiation in vitro and thus , several groups have hypothesized that men who systemically have lower levels of 1,25(OH)2D may be at increased risk for prostate cancer . To address this hypothesis , we evaluated the association of circulating concentrations of 1,25(OH)2D and its precursor 25-hydroxyvitamin D ( 25(OH)D ) with subsequent risk of prostate cancer . Methods : Prostate cancer cases were 460 men in the Health Professionals Follow-up Study who were diagnosed through 1998 after providing a blood specimen in 1993/95 . 90.2 % of the cases were organ confined or had minimal extraprostatic extension . An equal number of controls who had had a screening PSA test after blood draw  were individually matched to cases on age , history of a PSA test before blood draw , and time of day , season , and year of blood draw .  Plasma 1,25(OH)2D and 25(OH)D concentrations  were determined by radio-immunosorbant assay blindly to case – control status . Odds ratios ( OR ) of prostate cancer and 95 % confidence intervals ( CI ) were estimated from conditional logistic regression models mutually adjusting for quartiles of 1,25(OH)2D and 25(OH)D concentrations and for suspected prostate cancer risk factors . Quartile cutpoints were determined separately by season of blood draw using the distributions among controls . Results : Mean concentrations of 1,25(OH)2D and 25(OH)D were slightly , but not statistically significantly ( p= 0.06 and 0.20 , respectively ) , higher in cases ( 34.3 ± 7.1 pg/ml and 24.6 ± 7.7 ng/ml , respectively ) than in controls ( 33.5 ± 7.1 pg/ml and 23.9 ± 8.2 ng/ml , respectively ) . The OR of prostate cancer comparing men in the top to bottom quartile of 1,25(OH)2D was 1.25 ( 95 % CI : 0.82–1.90 , p-trend = 0.16 ) . For 25(OH)D the OR of prostate cancer comparing the top and bottom quartiles was 1.19 ( 95 % CI : 0.79–1.79 , p-trend = 0.59 ) . These findings did not vary by level of the other metabolite , age at diagnosis , family history of prostate cancer , or factors that are thought to influence 25(OH)D levels . Conclusion : In this prospect i ve study , we did not observe an inverse association between plasma concentrations of 1,25(OH)2D or 25(OH)D and incident prostate cancer , although we can not rule out potential effects at later stages of the disease There is strong epidemiological and laboratory evidence that vitamin D may be protective against colorectal neoplasia . Therefore , we sought to assess the relationship between serum 25(OH)D levels , dietary intake of vitamin D  , and  colorectal adenoma recurrence in our ursodeoxycholic acid trial . A total of 568 participants were r and omly selected for analysis of serum 25(OH)D levels . The range of total 25(OH)D was 5.5 - 66.1 ng/ml , with a median of 25.6 ng/ml . After categorizing 25(OH)D levels into tertiles based on the population distribution , the adjusted odds ratios ( 95 % CI ) for adenoma recurrence in the second and third tertiles were 0.88 ( 0.56 - 1.39 ) and 0.78 ( 0.49 - 1.24 ) , respectively . The association between serum 25(OH)D and adenoma recurrence appeared to be stronger among women than men . As compared to those below the median value , women with serum 25(OH)D levels above the median had an OR ( 95 % CI ) of 0.59 ( 0.30 - 1.16 ) ; the corresponding OR ( 95 % CI ) for men was 0.95 ( 0.60 - 1.49 ) . Analyses by dietary vitamin D intake revealed no statistically significant associations . In summary , the results of this study show a moderate , nonsignificant inverse association between serum 25(OH)D levels and reduced risk for colorectal adenoma recurrence , particularly among women BACKGROUND Although some observational studies have associated higher calcium intake and especially higher vitamin D intake and 25-hydroxyvitamin D levels with lower breast cancer risk , no r and omized trial has evaluated these relationships . METHODS Postmenopausal women ( N = 36 282 ) who were enrolled in a Women 's Health Initiative clinical trial were r and omly assigned to 1000 mg of elemental calcium with 400 IU of vitamin D(3 ) daily or placebo for a mean of 7.0 years to determine the effects of supplement use on incidence of hip fracture . Mammograms and breast exams were serially conducted . Invasive breast cancer was a secondary outcome . Baseline serum 25-hydroxyvitamin D levels were assessed in a nested case-control study of 1067 case patients and 1067 control subjects . A Cox proportional hazards model was used to estimate the risk of breast cancer associated with r and om assignment to calcium with vitamin D(3 ) . Associations between 25-hydroxyvitamin D serum levels and total vitamin D intake , body mass index ( BMI ) , recreational physical activity , and breast cancer risks were evaluated using logistic regression models . Statistical tests were two-sided . RESULTS Invasive breast cancer incidence was similar in the two groups ( 528 supplement vs 546 placebo ; hazard ratio = 0.96 ; 95 % confidence interval = 0.85 to 1.09 ) . In the nested case-control study , no effect of supplement group assignment on breast cancer risk was seen . Baseline 25-hydroxyvitamin D levels were modestly correlated with total vitamin D intake ( diet and supplements ) ( r = 0.19 , P < .001 ) and were higher among women with lower BMI and higher recreational physical activity ( both P < .001 ) . Baseline 25-hydroxyvitamin D levels were not associated with breast cancer risk in analyses that were adjusted for BMI and physical activity ( P(trend ) = .20 ) . CONCLUSIONS Calcium and vitamin D supplementation did not reduce invasive breast  cancer incidence in postmenopausal women . In addition , 25-hydroxyvitamin D levels were not associated with subsequent breast cancer risk . These findings do not support a relationship between total vitamin D intake and 25-hydroxyvitamin D levels with breast cancer risk BACKGROUND Calcium and vitamin D both appear to have antineoplastic effects in the large bowel . Although these nutrients are inter-related metabolically in bone and in the normal intestine , their potential interactions in large-bowel carcinogenesis are not well understood . METHODS We assessed independent and joint effects of calcium supplementation and vitamin D status on  adenoma recurrence in 803 subjects in a multi-center , placebo-controlled r and omized clinical trial of calcium supplementation for the prevention of colorectal adenoma recurrence . Serum levels of 25-hydroxy [ 25-(OH ) ] vitamin D and 1,25-dihydroxy [ 1,25-(OH)2 ] vitamin D levels were determined , and the Taq I and Fok I polymorphisms in the vitamin D receptor ( VDR ) gene were analyzed by polymerase chain reaction . Risk ratios ( RRs ) for any adenoma recurrence were computed for calcium supplementation within groups defined by serum vitamin D levels and for serum vitamin D levels within treatment groups . Associations of VDR polymorphisms with recurrence risk were also evaluated . All statistical tests were two-sided . RESULTS Among subjects with baseline 25-(OH ) vitamin D levels at or below the median ( 29.1 ng/mL ) , calcium supplementation was not associated with adenoma recurrence , whereas among those with levels above the median , calcium supplementation was associated with a reduced risk ( RR = 0.71 , 95 % confidence interval [ CI ] = 0.57 to 0.89 , P for interaction = .012 ) . Conversely , ser 
    Output:
    
In conclusion , a consistent inverse relationship between serum 25-hydroxyvitamin D levels and colorectal cancer was found .
No association was found for breast and prostate cancer