***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 Some evidence indicates that a low selenium intake may be associated with an increased risk of  prostate cancer .  OBJECTIVE The aim of this study was to investigate the association of plasma  selenium  concentration with subsequent prostate cancer risk and to examine this association by stage and grade of disease and other factors . DESIGN A nested case-control study was performed among men in the European Prospect i ve Investigation into Cancer and Nutrition ( EPIC ) . The association between plasma selenium concentration and prostate cancer risk was assessed in 959 men with incident prostate cancer and 1059 matched controls . RESULTS Overall , plasma selenium concentration was not associated with prostate cancer risk ; the multivariate relative risk for men in the highest fifth of selenium concentration compared with the lowest fifth was 0.96 ( 95 % CI : 0.70 , 1.31 ; P for trend = 0.25 ) . There were no significant differences in the association of plasma selenium with risk when analyzed by stage or grade of disease . Similarly , the association of selenium with risk did not differ by smoking status or by plasma alpha- or gamma-tocopherol concentration . CONCLUSION Plasma selenium concentration was not associated with prostate cancer risk in this large cohort of European men BACKGROUND Selenium is a potential chemopreventive agent against prostate cancer , whose chemoprotective effects are possibly mediated through the antioxidative properties of selenoenzymes . Interrelations with other antioxidative agents and oxidative stressors , such as smoking , are poorly understood . OBJECTIVES The aims were to investigate the association between serum  selenium  and prostate cancer risk and to examine interactions with other antioxidants and tobacco use . DESIGN A nested case-control study was performed within the screening arm of the Prostate , Lung , Colorectal , and Ovarian Cancer Screening Trial .  Serum selenium  in prospect ively collected sample s was compared between 724 incident prostate cancer case subjects and 879 control subjects , frequency-matched for age , time since initial screen , and year of blood draw . The men were followed for up to 8 y. RESULTS Overall , serum selenium was not associated with prostate cancer risk ( P for trend = 0.70 ) ; however , higher serum selenium was associated with lower risks in men reporting a high ( more than the median : 28.0 IU/d ) vitamin E intake [ odds ratio ( OR ) for the highest compared with the lowest quartile of selenium : 0.58 ; 95 % CI : 0.37 , 0.91 ; P for trend = 0.05 ; P for interaction = 0.01 ] and in multivitamin users ( OR for highest compared with the lowest quartile of selenium : 0.61 ; 95 % CI : 0.36 , 1.04 ; P for trend = 0.06 ; P for interaction = 0.05 ) . Furthermore , among smokers , high serum selenium concentrations were related to reduced prostate cancer risk ( OR for the highest compared with the lowest quartile of selenium : 0.65 ; 95 % CI : 0.44 , 0.97 ; P for trend = 0.09 ; P for interaction = 0.007 ) . CONCLUSION Greater prediagnostic serum selenium concentrations were not associated with prostate cancer risk in this large cohort , although greater concentrations were associated with reduced prostate cancer risks in men who reported a high intake of vitamin E  , in multivitamin users , and in smokers The threat of prostate cancer and the significant and often negative impact of its treatment underscore the importance of prevention . High- grade prostatic intraepithelial neoplasia ( HGPIN ) has been identified as a potential premalignant lesion marking an increased risk of prostate cancer and substantial evidence suggests that men with HGPIN are in need of prostate cancer prevention . In vitro , in vivo , epidemiologic , and clinical trial evidence that selenium supplementation protects against prostate cancer motivated the study we report here : a double-blind , r and omized ,  placebo-controlled  trial of selenium 200 ( μg/d ) as selenomethionine  in men with HGPIN . The primary endpoint was progression of HGPIN to prostate cancer over a 3-year period . This National Cancer Institute Intergroup trial was coordinated by the Southwest Oncology Group ( SWOG ) . Of 619 enrolled patients , 423 r and omized men with HGPIN ( 212 selenium and 211 placebo ) were eligible ( by central pathology review ) and included in the primary analysis . Three-year cancer rates were 36.6 % ( placebo ) versus 35.6 % ( selenium ; P = 0.73 , adjusted ) . The majority of patients who developed cancer  on trial ( 70.8 % , selenium and 75.5 % , placebo ) had a Gleason score of 6 or less than 6 ; there were no differences in Gleason scores between the two arms . Subset analyses included the finding of a nonsignificantly reduced prostate cancer risk ( relative risk = 0.82 ; 95 % CI : 0.40–1.69 ) in selenium versus placebo patients in the lowest quartile of baseline plasma selenium level ( < 106 ng/mL ) . Overall , and in all other subsets defined by baseline blood selenium levels , selenium supplementation had no effect on prostate cancer risk . The 36 % prostate cancer rate in men with HGPIN indicates the association of this lesion with an elevated prostate cancer risk . Future study in this setting should focus on selenium-deficient population s and selenium pharmacogenetics . Cancer Prev Res ; 4(11 ) ; 1761–9 . © 2011 AACR PURPOSE Men with prostate cancer are often advised to make changes in diet and lifestyle , although the impact of these changes has not been well documented . Therefore , we evaluated the effects of comprehensive lifestyle changes on prostate specific antigen ( PSA ) , treatment trends and serum stimulated LNCaP cell growth in men with early , biopsy proven prostate cancer after 1 year . MATERIAL S AND METHODS Patient recruitment was limited to men who had chosen not to undergo any conventional treatment , which provided an unusual opportunity to have a nonintervention r and omized control group to avoid the confounding effects of interventions such as radiation , surgery or and rogen deprivation therapy . A total of 93 volunteers with serum PSA 4 to 10 ng/ml and cancer Gleason scores less than 7 were r and omly assigned to an experimental group that was asked to make comprehensive lifestyle changes or to a usual care control group . RESULTS None of the experimental group patients but 6 control patients underwent conventional treatment due to an increase in PSA and /or progression of disease on magnetic resonance imaging . PSA decreased 4 % in the experimental group but increased 6 % in the control group ( p = 0.016 ) . The growth of LNCaP prostate cancer cells ( American Type Culture Collection , Manassas , Virginia ) was inhibited almost 8 times more by serum from the experimental than from the control group ( 70 % vs 9 % , p < 0.001 ) . Changes in serum PSA and also in LNCaP cell growth were significantly associated with the degree of change in diet and lifestyle . CONCLUSIONS Intensive lifestyle changes may affect the progression of early , low grade prostate cancer in men . Further studies and longer term followup are warranted The association between prostate cancer and baseline vitamin E and selenium was evaluated in the trial-based cohort of the Alpha-Tocopherol , Beta-Carotene Cancer Prevention Study ( n = 29,133 ) . During up to 9 years of follow-up , 317 men developed incident prostate cancer . Multivariate Cox proportional hazards models that adjusted for intervention group , benign prostatic hyperplasia , age , smoking , and urban residence were used to evaluate associations between prostate cancer and exposures of interest . There were no significant associations between baseline serum alpha-tocopherol , dietary vitamin E , or selenium and prostate cancer overall . The associations between prostate cancer and vitamin E and some of the baseline dietary tocopherols differed significantly by alpha-tocopherol intervention status , with the suggestion of a protective effect for total vitamin E among those who received the alpha-tocopherol intervention ( relative risk was 1.00 , 0.68 , 0.80 , and 0.52 for increasing quartiles ; P = 0.07 ) The Nutritional Prevention of Cancer Trial was a r and omized , clinical trial design ed to evaluate the efficacy of selenium as selenized yeast ( 200 microg daily ) in preventing the recurrence of nonmelanoma skin cancer among 1312 residents of the Eastern United States . Original secondary analyses through December 31 , 1993 showed striking inverse associations between treatment and the incidence of total [ hazard ratio ( HR ) = 0.61 , 95 % confidence interval ( CI ) = 0.46 - 0.82 ] , lung , prostate , and colorectal cancer and total cancer mortality . This report presents results through February 1 , 1996 , the end of blinded treatment . Effect modification by baseline characteristics is also evaluated . The effects of treatment overall and within subgroups of baseline age , gender , smoking status , and plasma selenium were examined using incidence rate ratios and Cox proportional hazards models . Selenium supplementation reduced total ( HR = 0.75 , 95 % CI = 0.58 - 0.97 ) and prostate ( HR = 0.48 , 95 % CI = 0.28 - 0.80 ) cancer incidence but was not significantly associated with lung ( HR = 0.74 , 95 % CI = 0.44 - 1.24 ) and colorectal ( HR = 0.46 , 95 % CI = 0.21 - 1.02 ) cancer incidence . The effects of treatment on other site-specific cancers are also described . The protective effect of selenium was confined to males ( HR = 0.67 , 95 % CI = 0.50 - 0.89 ) and was most pronounced in former smokers . Participants with baseline plasma selenium concentrations in the lowest two tertiles ( < 121.6 ng/ml ) experienced reductions in total cancer incidence , whereas those in the highest tertile showed an elevated incidence ( HR = 1.20 , 95 % CI = 0.77 - 1.86 ) . The Nutritional Prevention of Cancer trial continues to show a protective effect of selenium  on cancer incidence , although not all site-specific cancers exhibited a reduction in incidence . This treatment effect was restricted to males and to those with lower baseline plasma selenium concentrations CONTEXT Secondary analyses of 2 r and omized controlled trials and supportive epidemiologic and pre clinical data indicated the potential of selenium and vitamin E for preventing prostate cancer . OBJECTIVE To determine whether selenium , vitamin E , or both could prevent prostate cancer and other diseases with little or no toxicity in relatively healthy men . DESIGN , SETTING , AND PARTICIPANTS A r and omized , placebo-controlled trial ( Selenium and Vitamin E Cancer Prevention Trial [ SELECT ] ) of 35,533 men from 427 participating sites in the United States , Canada , and Puerto Rico r and omly assigned to 4 groups ( selenium , vitamin E , selenium + vitamin E , and placebo ) in a double-blind fashion between August 22 , 2001 , and June 24 , 2004 . Baseline eligibility included age 50 years or older ( African American men ) or 55 years or older ( all other men ) , a serum prostate-specific antigen level of 4 ng/mL or less , and a digital rectal examination not suspicious for prostate cancer . INTERVENTIONS Oral selenium ( 200 microg/d from L-selenomethionine ) and matched vitamin E placebo , vitamin E ( 400 IU/d of all rac-alpha-tocopheryl acetate ) and matched selenium placebo , selenium + vitamin E , or placebo + placebo for a planned follow-up of minimum of 7 years and a maximum of 12 years . MAIN OUTCOME MEASURES Prostate cancer and prespecified secondary outcomes , including lung , colorectal , and overall primary cancer . RESULTS As of October 23 , 2008 , median overall follow-up was 5.46 years ( range , 4.17 - 7.33 years ) . Hazard ratios ( 99 % confidence intervals [ CIs ] ) for prostate cancer were 1.13 ( 99 % CI , 0.95 - 1.35 ; n = 473 ) for vitamin E , 1.04 ( 99 % CI , 0.87 - 1.24 ; n = 432 ) for selenium , and 1.05 ( 99 % CI , 0.88 - 1.25 ; n = 437 ) for selenium + vitamin E vs 1.00 ( n = 416 ) for placebo . There were no significant differences ( all P>.15 ) in any other prespecified cancer end points . There were statistically nonsignificant increased risks of prostate cancer in the vitamin E group ( P = .06 ) and type 2 diabetes mellitus in the selenium group ( relative risk , 1.07 ; 99 % CI , 0.94 - 1.22 ; P = .16 ) but not in the selenium + vitamin E group . CONCLUSION Selenium or vitamin E , alone or in combination at the doses and formulations used , did not prevent prostate cancer in this population of relatively healthy men . TRIAL REGISTRATION clinical trials.gov identifier : NCT00006392 Results of a r and omized controlled trial have suggested a protective effect of  selenium  against  prostate cancer .  Few 
    Output:
    
Conclusions : This meta- analysis indicated that selenium most probably has a protective role against development of prostate cancer and its progression to advanced stages .
Therefore , selenium supplementation can be proposed for prevention of prostate cancer