***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: PURPOSE We report magnetic resonance imaging findings among unselected men with low risk prostate cancer before active surveillance . MATERIAL S AND METHODS We prospect ively enrolled men with low grade , low risk , localized prostate cancer . All patients underwent multiparametric endorectal coil magnetic resonance imaging and were offered confirmatory biopsy within 1 year of imaging . The primary outcome was the impact of magnetic resonance imaging on identifying patients who were reclassified by confirmatory biopsy as no longer fulfilling active surveillance criteria . We further identified clinical parameters associated with reclassification . The cohort was stratified as patients with 1 ) normal magnetic resonance imaging , 2 ) cancer on magnetic resonance imaging concordant with initial biopsy ( less than 1 cm ) and 3 ) cancer on magnetic resonance imaging larger than 1 cm . We performed univariate analysis to assess differences in clinical parameters among the groups . RESULTS Magnetic resonance imaging did not detect cancer in 23 cases ( 38 % ) while magnetic resonance imaging and initial biopsy were concordant in 24 ( 40 % ) . Magnetic resonance imaging detected a 1 cm or larger lesion in 13 patients ( 22 % ) . Of the cases 18 ( 32.14 % ) were reclassified . When no cancer was identified on magnetic resonance imaging , only 2 cases ( 3.5 % ) were reclassified . The positive and negative predictive values for magnetic resonance imaging predicting reclassification were 83 % ( 95 % CI 73 - 93 ) and 81 % ( 95 % CI 71 - 91 ) , respectively . Prostate specific antigen density was increased in patients with lesions larger than 1 cm on magnetic resonance imaging compared to those with no cancer on imaging ( median 0.15 vs 0.07 ng/ml/cc , p=0.016 ) . CONCLUSIONS Magnetic resonance imaging appears to have a high yield for predicting reclassification among men who elect active surveillance . Upon confirmation of our results magnetic resonance imaging may be used to better select and guide patients before active surveillance BACKGROUND The effectiveness of surgery versus observation for men with localized prostate cancer detected by means of prostate-specific antigen ( PSA ) testing is not known . METHODS From November 1994 through January 2002 , we r and omly assigned 731 men with localized prostate cancer ( mean age , 67 years ; median PSA value , 7.8 ng per milliliter ) to radical prostatectomy or observation  and followed them through January 2010 . The primary outcome was all-cause mortality ; the secondary outcome was prostate-cancer mortality . RESULTS During the median follow-up of 10.0 years , 171 of 364 men ( 47.0 % ) assigned to radical prostatectomy  died , as compared with 183 of 367 ( 49.9 % ) assigned to observation ( hazard ratio , 0.88 ; 95 % confidence interval [ CI ] , 0.71 to 1.08 ; P=0.22 ; absolute risk reduction , 2.9 percentage points ) . Among men assigned to radical prostatectomy , 21 ( 5.8 % ) died from prostate cancer or treatment , as compared with 31 men ( 8.4 % ) assigned to observation ( hazard ratio , 0.63 ; 95 % CI , 0.36 to 1.09 ; P=0.09 ; absolute risk reduction , 2.6 percentage points ) . The effect of treatment on all-cause and prostate-cancer mortality did not differ according to age , race , coexisting conditions , self-reported performance status , or histologic features of the tumor . Radical prostatectomy was associated with reduced all-cause mortality among men with a PSA value greater than 10 ng per milliliter ( P=0.04 for interaction ) and possibly among those with intermediate-risk or high-risk tumors ( P=0.07 for interaction ) . Adverse events within 30 days after surgery occurred in 21.4 % of men , including one death . CONCLUSIONS Among men with localized prostate cancer detected during the early era of PSA testing  , radical prostatectomy did not significantly reduce all-cause or prostate-cancer mortality , as compared with observation , through at least 12 years of follow-up . Absolute differences were less than 3 percentage points . ( Funded by the Department of Veterans Affairs Cooperative Studies Program and others ; PIVOT Clinical Trials.gov number , NCT00007644 . ) OBJECTIVE Screening practice s for prostate cancer have result ed in an increasing incidence of prostate cancers . Our knowledge about which prostate cancers are life threatening and which are not is limited . Thus , for ethical , medical , and economic reasons we need to define which patients can be managed by active surveillance . METHODS From 1993 through 1999 , men from the Rotterdam section of the European R and omized study of Screening for Prostate Cancer ( ERSPC ) were screened by two strict protocol s , which were based on prostate-specific antigen ( PSA ) , digital rectal examination , and transrectal ultrasound . For this study , men with criteria that reflect current active surveillance studies were selected : those with a biopsy Gleason score < or = 3 + 3 in two or fewer cores , with a PSA density < 0.2 and a maximum PSA-level of 15 ng/ml . Clinical stage had to be T1C or T2 . RESULTS Of the 1,014 prostate cancers detected in the prevalence screen , 293 men ( 28.9 % ) met the criteria for active surveillance . Their mean age was 65.7 and the mean PSA level was 4.8 ng/ml .  Radical prostatectomy was elected by 136 men ( 46.4 % ) , radiotherapy by 91 ( 31.1 % ) , and watchful waiting by 64 ( 21.8 % ) . The mean follow-up was 80.8 months . The eight-year prostate cancer-specific survival was 99.2 % ; the overall survival was 85.4 % . Nineteen men who chose watchful waiting changed to definitive treatment during follow-up . CONCLUSION Only three men died of prostate cancer , none of whom were on watchful waiting . Our observations provide preliminary validation of the arbitrary selection criteria for active surveillance BACKGROUND The incidence of small , localised , well-differentiated prostate cancer ( PCa ) is increasing , mainly as a result of screening . Many of these cancers will not progress , and radical therapy may lead to substantial overtreatment . Active surveillance ( AS ) has emerged as an alternative . OBJECTIVE To retrospectively vali date the currently used criteria for eligibility for AS . DESIGN , SETTING , AND PARTICIPANTS For this cohort study , data from 616 men who were diagnosed with PCa between 1994 and 2007 at a mean age of 66.3 yr in four centres of the European R and omized Study of Screening for Prostate Cancer ( ERSPC ) were combined . All patients fit the criteria for AS ( prostate-specific antigen [ PSA ] < or = 10.0 ng/ml , PSA-density < 0.2 ng/ml per ml , stage T1C/T2 , Gleason score < or = 3 + 3 = 6 , and < or = 2 positive biopsy cores ) , and initially they were managed expectantly . Median follow-up was 3.91 yr . MEASUREMENTS Disease specific- , overall- , and treatment-free survival were studied . Present PSA characteristics were assessed and also compared between men who were switching to deferred active therapy during follow-up and men remaining untreated . RESULTS AND LIMITATIONS The calculated ( Kaplan-Meier ) 10-yr PCa-specific survival ( 21 patients at risk ) was 100 % , which sharply contrasted with 77 % overall survival . Men still alive showed favourable PSA characteristics . Although the calculated 10-yr treatment-free survival was only 43 % , objective signs of progression often did not indicate the shift to radical treatment . The cohort consisted of men on AS and those on watchful waiting ( WW ) ; information on comorbidity or psychological distress was not available . CONCLUSIONS AS seems justified in selected men with screen-detected PCa . Prospect i ve protocol -based AS programs are necessary to optimise selection criteria and to find the appropriate trigger points for switching to active therapy . Possible negative psychological reactions with AS against improved quality of life by withholding side-effects from radical treatment should be considered Active surveillance followed by selective treatment for men who have evidence of disease progression may be an option for select patients with early‐stage prostate cancer . In this article , the authors report their experience in a contemporary cohort of men with prostate cancer who were managed with active surveillance PURPOSE  Prostate specific antigen doubling time was used to stratify patients into groups at low and high risk for progression . The prostate specific antigen kinetics in these 2 groups were modeled . MATERIAL S AND METHODS In this prospect i ve , single-arm cohort study patients with favorable clinical parameters ( stage T1b-T2b N0M0 , Gleason score 7 or less , prostate specific antigen 15 ng/ml or less ) were conservatively treated with watchful waiting . Evolution of  serial prostate specific antigen measurements  over time was estimated from a general linear mixed model of the natural log of prostate specific antigen . The corresponding average and individual prostate specific antigen doubling times were also calculated . RESULTS Since November 1995 a total of 231 patients had at least 6 months of followup and at least 3 prostate specific antigen measurements . Based on prostate specific antigen doubling time and repeat biopsy , 93 patients fulfilled the criteria for high risk of disease progression and 138 were defined as low risk . Given the baseline status of these individuals , 2 reference average lines ( high risk and low risk ) were derived to model the evolution of prostate specific antigen levels and permit more rational decision making regarding the need for definitive intervention . The average prostate specific antigen doubling time was 2.97 years ( 95 % CI 2.2 - 4.4 ) in patients allocated to the high risk group and 6.54 years ( 95 % CI 4.8 - 12.3 ) in those at low risk . CONCLUSIONS By applying the dynamic prognostic rule in combination with serial biopsy , a rational decision for definitive intervention based on the risk of disease progression could be optimally recommended about 2.3 years after initiated surveillance BACKGROUND We aim ed to investigate the safety and efficacy of dutasteride , a 5α-reductase inhibitor , on prostate cancer progression in men with low-risk disease who chose to be followed up with active surveillance . METHODS In our 3 year , r and omised , double-blind , placebo-controlled study , undertaken at 65 academic medical centres or outpatient clinics in North America , we enrolled men aged 48 - 82 years who had low-volume , Gleason score 5 - 6 prostate cancer and had chosen to be followed up with active surveillance . We r and omly allocated participants in a one-to-one ratio , stratified by site and in block sizes of four , to receive once-daily dutasteride 0·5 mg or matching placebo . Participants were followed up for 3 years , with 12-core prostate biopsy sample s obtained after 18 months and 3 years . The primary endpoint was time to prostate cancer progression , defined as the number of days between the start of study treatment and the earlier of either pathological progression ( in patients with ≥1 biopsy assessment after baseline ) or therapeutic progression ( start of medical therapy ) . This trial is registered with Clinical Trials.gov , number NCT00363311 . FINDINGS Between Aug 10 , 2006 , and March 26 , 2007 , we r and omly allocated 302 participants , of whom 289 ( 96 % ) had at least one biopsy procedure after baseline and were included in the primary analysis . By 3 years , 54 ( 38 % ) of 144 men in the dutasteride group and 70 ( 48 % ) of 145 controls had prostate cancer progression ( pathological or therapeutic ; hazard ratio 0·62 , 95 % CI 0·43 - 0·89 ; p=0·009 ) . Incidence of adverse events was much the same between treatment groups . 35 ( 24 % ) men in the dutasteride group and 23 ( 15 % ) controls had sexual adverse events or breast enlargement or tenderness . Eight ( 5 % ) men in the dutasteride group and seven ( 5 % ) controls had cardiovascular adverse events , but there were no prostate cancer-related deaths or instances of metastatic disease . INTERPRETATION Dutasteride could provide a beneficial adjunct to active surveillance for men with low-risk prostate cancer . FUNDING GlaxoSmithKline PURPOSE We evaluated expectant management of prostate cancer with definitive treatment deferred until evidence of cancer progression in men with low risk , localized cancers . MATERIAL S AND METHODS We retrospectively review ed prospect ively entered data base records . Patients with low risk cancer who were eligible for definitive therapy but chose deferred management between 1984 and 2001 composed the cohort . Followup included regular evaluations to detect progression by  prostate specific antigen ( PSA ) , digital rectal examination , transrectal ultrasound and prostate biopsy .  Objective progression was defined by a point scale of changes in prognostic factors . Definitive treatment was recommended in patients with objective progression . RESULTS The cohort comprised 88 patients with clinical stages T1 - 2 , NX0 , M0 prostate 
    Output:
    
The working group concluded that for patients with low-risk ( Gleason score ≤6 ) localized prostate cancer , AS is the preferred disease management strategy .
Active treatment ( RP or RT ) is appropriate for patients with intermediate-risk ( Gleason score 7 ) localized prostate cancer .
For select patients with low-volume Gleason 3 + 4=7 localized prostate cancer , AS can be considered