***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: Prognosis studies are investigations of future events or the evaluation of associations between risk factors and health outcomes in population s of patients ( 1 ) . The results of such studies improve our underst and ing of the clinical course of a disease and assist clinicians in making informed decisions about how best to manage patients . Prognostic research also informs the design of intervention studies by helping define subgroups of patients who may benefit from a new treatment and by providing necessary information about the natural history of a disorder ( 2 ) . There has recently been a rapid increase in the use of systematic review methods to synthesize the evidence on research questions related to prognosis . It is essential that investigators conducting systematic review s thoroughly appraise the method ologic quality of included studies to be confident that a study 's design , conduct , analysis , and interpretation have adequately reduced the opportunity for bias ( 3 , 4 ) . Caution is warranted , however , because inclusion of method ologically weak studies can threaten the internal validity of a systematic review ( 4 ) . This follows abundant empirical evidence that inadequate attention to biases can cause invalid results and inferences ( 5 - 9 ) . However , there is limited consensus on how to appraise the quality of prognosis studies ( 1 ) . A useful framework to assess bias in such studies follows the basic principles of epidemiologic research ( 10 , 11 ) . We focus on 6 areas of potential bias : study participation , study attrition , prognostic factor measurement , confounding measurement and account , outcome measurement , and analysis . The main objectives of our review of review s are to describe methods used to assess the quality of prognosis studies and to describe how well current practice s assess potential biases . Our secondary objective is to develop recommendations to guide future quality appraisal , both within single studies of prognostic factors and within systematic review s of the evidence . We hope this work facilitates future discussion and research on biases in prognosis studies and systematic review s. Methods Literature Search and Study Selection We identified systematic review s of prognosis studies by search ing MEDLINE ( 1966 to October 2005 ) using the search strategy recommended by McKibbon and colleagues ( 12 ) . This strategy combines broad search terms for systematic review s ( systematic review .mp ; meta- analysis .mp ) and a sensitive search strategy for prognosis studies ( cohort , incidence , mortality , follow-up studies , prognos * , predict * , or course ) . We also search ed the reference lists of included review s and method ologic papers to identify other relevant publications . We restricted our search to English- language publications . One review er conducted the search and selected the studies . Systematic review s , defined as review s of published studies with a comprehensive search and systematic selection , were included if they assessed the method ologic quality of the included studies by using 1 or more explicit criteria . We excluded studies if they were meta-analyses of independent patient data only , if their primary goal was to investigate the effectiveness of an intervention or specific diagnostic or screening tests , or if they included studies that were not done on humans . Data Extraction and Synthesis Individual items included in the quality assessment of the systematic review s were recorded as they were reported in the publication ( that is , the information that would be available to readers and future review ers ) . We review ed journal Web sites and contacted the authors of the systematic review s for additional information when authors made such an offer in their original papers . When review s assessed different study design s by using different sets of quality items , we extracted only those items used to assess cohort studies . We constructed a comprehensive list of distinct items that the review s used to assess the quality of their included studies . The full text of each review was screened . All items used by the review authors to assess the quality of studies were extracted into a computerized spreadsheet by 1 review er . Two experienced review ers , a clinical epidemiologist and an epidemiologist , independently synthesized the quality items extracted from the prognosis review s to determine how well the systematic review s assessed potential biases . We did this in 3 steps : 1 ) identified distinct concepts or domains addressed by the quality items ; 2 ) grouped each extracted quality item into the appropriate domain or domains ; and 3 ) identified the domains necessary to assess potential biases in prognosis studies . We then used this information to assess how well the review s ' quality assessment included items from the domains necessary to assess potential biases . After completing each of the first 3 steps , the review ers met to attempt to reach a consensus . The consensus process involved each review er presenting his or her observations and results , followed by discussion and debate . A third review er was available in cases of persistent disagreement or uncertainty . In the first step , all domains addressed by the quality items were identified . The first review er iteratively and progressively defined the domains as items were extracted from the included review s. The second review er defined domains from a r and om list of all extracted quality items . Limited guidance was provided to the review ers so that their assessment s and definitions of domains would be independent . The review ers agreed on a final set of domains that adequately and completely defined all of the extracted items . In the second step , review ers independently grouped each extracted item into the appropriate domains . Review ers considered each extracted item by asking , What is each particular quality item addressing ? or What are the review 's authors getting at with the particular quality assessment item ? . Items were grouped into the domain or domains that best represented the concepts being addressed . For example , the extracted items at least 80 % of the group originally identified was located for follow-up and follow-up was sufficiently complete or does n't jeopardize validity were each independently classified by both review ers as assessing the domain completeness of follow-up adequate , whereas the extracted item quantification and description of all subjects lost to follow-up was classified as assessing the domain completeness of follow-up described . In the third step , we identified the domains necessary to assess potential biases . Each review er considered the ability of the identified domains to adequately address , at least in part , 1 of the following 6 potential biases : 1 ) study participation , 2 ) study attrition , 3 ) prognostic factor measurement , 4 ) confounding measurement and account , 5 ) outcome measurement , and 6 ) analysis . Domains were considered to adequately address part of the framework if information garnered from that domain would inform the assessment of potential bias . For example , both review ers judged that the identified domain study population represents source population or population of interest assessed potential bias in a prognosis study , whereas the domain research question definition did not , although the latter is an important consideration in assessing the inclusion of studies in a systematic review . Finally , on the basis of our previous ratings , we looked at whether each review included items from the domains necessary to assess the 6 potential biases . We calculated the frequency of systematic review s by assessing each potential bias and the number of review s that adequately assessed bias overall . From this systematic synthesis , we developed recommendations for improving quality appraisal in future systematic review s of prognosis studies . We used Microsoft Access and Excel 2002 ( Microsoft Corp. , Redmond , Washington ) for data management and SAS for Windows , version 9.1 ( SAS Institute , Inc. , Cary , North Carolina ) for descriptive statistics . Role of the Funding Sources The funding sources , the Canadian Institutes of Health Research , the Canadian Chiropractic Research Foundation , the Ontario Chiropractic Association , and the Ontario Ministry of Health and Long Term Care , did not have a role in the collection , analysis , or interpretation of the data or in the decision to su bmi t the manuscript for publication . Results We identified 1384 potentially relevant articles . Figure 1 shows a flow chart of studies that were included and excluded . Figure 2 shows the number of review s identified by year of publication . We excluded 131 systematic review s of prognosis studies that did not seem to include any quality assessment of the included studies ; this represented 44 % of prognosis review s. We included 163 review s of prognosis studies in our analysis ( 13 - 175 ) . The most common topics were cancer ( 15 % ) , musculoskeletal disorders and rheumatology ( 13 % ) , cardiovascular ( 10 % ) , neurology ( 10 % ) , and obstetrics ( 10 % ) . Other review s included a wide range of health and health care topics . Sixty-three percent of the review s investigated the association between a specific prognostic factor and a particular outcome ; the remainder investigated multiple prognostic factors or models . The number of primary studies included in each systematic review ranged from 3 to 167 ( median , 18 [ interquartile range , 12 to 31 ] ) . A complete description of the included review s is available from the authors on request . Figure 1 . Flow diagram of inclusion and exclusion criteria of systematic review s. Figure 2 . Number of systematic review s of prognosis studies identified over time . Quality Items One hundred fifty-three review s provided adequate detail to allow extraction of quality items . Eight hundred eighty-two distinct quality items were extracted from the review s. Most review s developed their own set of quality items , with only a few applying criteria from previous review s. Most quality items BACKGROUND Blockade of programmed death 1 ( PD-1 ) , an inhibitory receptor expressed by T cells , can overcome immune resistance . We assessed the antitumor activity and safety of BMS-936558 , an antibody that specifically blocks PD-1 . METHODS We enrolled patients with advanced melanoma , non-small-cell lung cancer , castration-resistant prostate cancer , or renal-cell or colorectal cancer to receive anti-PD-1 antibody at a dose of 0.1 to 10.0 mg per kilogram of body weight every 2 weeks . Response was assessed after each 8-week treatment cycle . Patients received up to 12 cycles until disease progression or a complete response occurred . RESULTS A total of 296 patients received treatment through February 24 , 2012 .  Grade 3 or 4 drug-related adverse events occurred in 14 % of patients ; there were three deaths from pulmonary toxicity . No maximum tolerated dose was defined . Adverse events consistent with immune-related causes were observed . Among 236 patients in whom response could be evaluated , objective responses ( complete or partial responses ) were observed in those with non-small-cell lung cancer , melanoma , or renal-cell cancer .  Cumulative response rates ( all doses ) were 18 % among patients with non-small-cell lung cancer ( 14 of 76 patients ) , 28 % among patients with melanoma ( 26 of 94 patients ) , and 27 % among patients with renal-cell cancer ( 9 of 33 patients ) . Responses were durable ; 20 of 31 responses lasted 1 year or more in patients with 1 year or more of follow-up . To assess the role of intratumoral PD-1 lig and ( PD-L1 ) expression in the modulation of the PD-1-PD-L1 pathway , immunohistochemical analysis was performed on pretreatment tumor specimens obtained from 42 patients . Of 17 patients with PD-L1-negative tumors , none had an objective response ; 9 of 25 patients ( 36 % ) with PD-L1-positive tumors had an objective response ( P=0.006 ) . CONCLUSIONS Anti-PD-1 antibody produced objective responses in approximately one in four to one in five patients with non-small-cell lung cancer , melanoma , or renal-cell cancer ; the adverse-event profile does not appear to preclude its use . Preliminary data suggest a relationship between PD-L1 expression on tumor cells and objective response . ( Funded by Bristol-Myers Squibb and others ; Clinical Trials.gov number , NCT00730639 . ) BACKGROUND T-cell infiltration in estrogen receptor (ER)-negative breast tumours has been associated with longer survival . To investigate this association and the potential of tumour T-cell infiltration as a prognostic and predictive marker , we have conducted the largest study of T cells in breast cancer to date . PATIENTS AND METHODS Four studies totalling 12 439 patients were used for this work . Cytotoxic ( CD8 + ) and regulatory ( forkhead box protein 3 , FOXP3 + ) T cells were quantified using immunohistochemistry ( IHC ) . IHC for CD8  was conducted using available material from all four studies ( 8978 sample s ) and for FOXP3 from three studies ( 5239 sample s)-multiple imputation was used to resolve missing data from the remaining patients . Cox regression was used to test for associations with breast cancer-specific survival . RESULTS In ER-negative tumours [ triple-negative breast cancer and human epidermal growth factor receptor 2 ( human epidermal growth factor receptor 2 ( HER2 ) positive ) ] , presence of CD8 + T cells within the tumour was associated with a 28 % [ 95 % confidence interval ( CI ) 16 % to 38 % ] reduction in the hazard of breast cancer-specific mortality , and CD8 + T cells within the stroma with a 21 % ( 95 % CI 7 % to 33 % ) reduction in hazard . In ER-positive HER2-positive tumours , CD8 + T cells within the tumour were associated with a 27 % ( 95 % CI 4 % to 44 % ) reduction in hazard . In ER-negative disease , there was evidence for greater benefit from anthracyclines in the National Epirubicin Adjuvant Trial in patients with CD8 + tumours [ hazard ratio ( HR ) = 0.54 ; 95 % CI 0.37 - 0.79 ] versus CD8-negative tumours ( HR = 0.87 ; 95 % CI 0.55 - 1.38 ) . The difference in effect between these subgroups was significant when limited to cases with complete data ( P heterogeneity = 0.04 ) and approached significance in imputed data ( P heterogeneity = 0.1 ) . CONCLUSIONS The presence of CD8 + T cells in breast cancer is associated with a significant reduction in the relative risk of death from disease in both the ER-negative [ supplementary Figure S1 , available at Annals of Oncology online ] and the ER-positive HER2-positive subtypes . Tumour lymphocytic infiltration may improve risk stratification in breast cancer patients classified into these subtypes . NEAT Clinical Tri 
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Discussion Immunomodulation seems to be a promising strategy in solid tumors .
PD-1 and PD-L1 are key physiologic suppressors of the cytotoxic immune reaction .