***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 Treatment with cetuximab , a monoclonal antibody directed against the epidermal growth factor receptor , improves overall and progression-free survival and preserves the quality of life in patients with colorectal cancer that has not responded to chemotherapy . The mutation status of the K-ras gene in the tumor may affect the response to cetuximab and have treatment-independent prognostic value . METHODS We analyzed tumor sample s , obtained from 394 of 572 patients ( 68.9 % ) with colorectal cancer who were r and omly assigned to receive cetuximab plus best supportive care or best supportive care alone  , to look for activating mutations in exon 2 of the K-ras gene . We assessed whether the mutation status of the K-ras gene was associated with survival in the cetuximab and supportive-care groups . RESULTS Of the tumors evaluated for K-ras mutations , 42.3 % had at least one mutation in exon 2 of the gene . The effectiveness of cetuximab was significantly associated with K-ras mutation status ( P=0.01 and P<0.001 for the interaction of K-ras mutation status with overall survival and progression-free survival , respectively ) . In patients with wild-type K-ras tumors , treatment with cetuximab as compared with supportive care alone significantly improved overall survival ( median , 9.5 vs. 4.8 months ; hazard ratio for death , 0.55 ; 95 % confidence interval [ CI ] , 0.41 to 0.74 ; P<0.001 ) and progression-free survival ( median , 3.7 months vs. 1.9 months ; hazard ratio for progression or death , 0.40 ; 95 % CI , 0.30 to 0.54 ; P<0.001 ) . Among patients with mutated K-ras tumors , there was no significant difference between those who were treated with cetuximab and those who received supportive care alone with respect to overall survival ( hazard ratio , 0.98 ; P=0.89 ) or progression-free survival ( hazard ratio , 0.99 ; P=0.96 ) . In the group of patients receiving best supportive care alone , the mutation status of the K-ras gene was not significantly associated with overall survival ( hazard ratio for death , 1.01 ; P=0.97 ) . CONCLUSIONS Patients with a colorectal tumor bearing mutated K-ras did not benefit from cetuximab , whereas patients with a tumor bearing wild-type K-ras did benefit from cetuximab . The mutation status of the K-ras gene had no influence on survival among patients treated with best supportive care alone . ( Clinical Trials.gov number , NCT00079066 . Support for prospect i ve registration of protocol s for systematic review s has been gathering momentum . The PRISMA statement , a guideline for reporting systematic review s and meta-analyses of studies that evaluate health-care interventions , advocates registration . Well-conducted systematic review s are accepted as the best- quality evidence to inform policy and practice , and the dramatic upward trend in the number of systematic review s published annually ( fi gure ) is set to continue . However , there is currently no single facility for identifying this type of research in advance of the appearance of the results of the review . There is concern about and evidence of publication and selective outcome -reporting biases associated with systematic review s. An open registry of review s captured at the protocol stage would facilitate good practice in systematic review s by providing transparency of the review process and outcomes . Discrepancies between the methods of the published review and those planned in the registered protocol could be more readily identifi ed . Registration might also encourage full publication of the review ’s fi ndings and transparency in changes to methods that could bias fi ndings . In both the prevention and revelation of potential bias , registration should improve quality and increase confi dence that policy or practice informed by the fi ndings of systematic review s are indeed drawing on best- quality evidence . A registry of protocol s of systematic review s could assist those planning new review s and updating existing ones . Easy access to information about ongoing review s should help to optimise the use of fi nite re sources by enabling funding and commissioning agencies to avoid unnecessary duplication and encourage collaboration . A comprehensive registry could also create opportunities for method ological and other research , both within and across disciplines . Existing access to systematic - review protocol s is limited to the outputs of individual organisations , such as the Cochrane and Campbell Collaborations and the Joanna Briggs Institute . The National Public Health Service for Wales is piloting an All Wales Systematic Review s Register , but , up to now , there has been no central ised comprehensive registry of systematic - review protocol s. We are developing an international facility to register the details of ongoing systematic review s in health and social care . Our registry is being established with the existing platform and infrastructure that supports the Data base of Abstract s of Review s of Eff ects ( DARE ) , the NHS Economic Evaluations Data base ( NHS EED ) and the Health Technology Assessment ( HTA ) data base produced by the Centre for Review s and Dissemination . The initial scope of the registry will be limited to systematic review s of the eff ectiveness of health interventions . However , the longterm aim is for the registry to include details of all ongoing systematic review s with a health-related outcome in the broadest sense . Ultimately , inclusion will encompass systematic review s of health-care interventions , and review s of the social determinants of health , of service delivery , and of risk factors and genetic associations . Our web-based registry will off er free public access , be electronically search able , and open to all prospect i ve registrants . Registration will require the provision of a minimum data set , the completeness of which will be checked automatically before registration . After acceptance , the registry ’s entry and protocol for the review , if available , will be loaded on the data base as a permanent entry and a unique identifi cation number issued . An audit trail for any amendments to the information will be available within the record . Links to result ing publications will be added . These provisions ensure that the registry will match the relevant criteria required of clinical trials registries 
    Output:
    
We did not observe any significant association between overall or progression-free survival , neither when considering all colorectal cancer patients nor for subgroup analyses ( metastatic , anti-EGFR [ epidermal growth factor receptor ] treatment , or KRAS wild type ) .
We have found no clear evidence to support an association between the KRAS-LCS6 genotype and overall or progression-free survival among colorectal cancer patients , even after conducting subgroup analyses by stage and anti-EGFR treatment status .