***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: Introduction This study aims to search for independent predictors of lateral node metastasis in low rectal cancers . Material s and methods We analyzed 1,046 patients who underwent curative resection for lower rectal cancer in our prospect ively collected data base .  All lymph nodes were dissected from the fresh specimen , and their locations were documented prospect ively according to the classification by the Japanese Society of Cancer of the Colon and Rectum . Results More than 35 % of the patients had demonstrated upward nodal metastasis in the direction of the inferior mesenteric vessels , while 11 % demonstrated lateral node metastasis , which was present in 17.3 % of patients with T3 and T4 lesions . Multivariate analysis revealed five factors to be statistically significant independent predictors of lateral node metastasis : female sex , tumors that were not well differentiated , pathological T3 and above , positive microscopic lymphatic invasion , and positive mesorectal nodes . Using the variables sex , differentiation , T stage , and mesorectal nodes as risk factors , because these could be eluci date d preoperatively , the presence of lateral node metastasis was then analyzed according to the number of positive risk factors . When there were fewer than three positive factors , the risk of lateral nodal spread was low ( 4.5 % ) . When three or more risk factors were positive , the odds of lateral node metastasis were more than 7.5 times higher ( p < 0.001 ) . Conclusion The findings of this study provide a scoring system that can be used to guide the clinician to the presence of lateral node metastasis in low rectal cancers Purpose This study aims to determine the risk factors for lateral pelvic recurrence ( LPR ) in rectal cancer patients treated with neoadjuvant chemoradiotherapy ( CRT ) and curative surgery .  Methods Four hundred forty-three patients treated with neoadjuvant CRT and curative surgery from October 1999 through June 2009 were analyzed . All patients underwent total mesorectal resection without lateral pelvic lymph node ( LPLN ) dissection .  Recurrence patterns and lateral pelvic recurrence-free survival ( LPFS ) were evaluated relative to clinicopathologic parameters including pelvic LN status . Results Median follow-up was 52 months , with locoregional recurrence in 53 patients ( 11.9 % ) . Of the 53 patients , 28 ( 52.8 % ) developed LPR , of which eight had both central and lateral PR . Multivariate analysis showed a significant relationship between LPFS and the number of lateral pelvic LN ( p = 0.010 ) as well as the ratio of the number of positive LN/number of dissected LN ( p = 0.038 ) . The relationship between LPFS and LPLN size had a marginal trend ( p = 0.085 ) . Logistic regression analysis showed positive relationships between LPR probability and the number of LPLN ( odds ratio [ OR ] 1.507 ; 95 % confidence interval [ CI ] 1.177–1.929 ; p = 0.001 ) as well as LPLN size ( OR 1.124 ; CI 1.029–1.227 , p = 0.009 ) . Conclusions LPLN ≥ 2 and a ratio of the number of positive LN/number of dissected LN > 0.3 were prognostic of poor LPFS . The prediction curve of LPR according to the number and size of LPLN could be useful for determining the benefit of additional lateral pelvic treatment Purpose The aims of the study were to determine the extent of male sexual dysfunction after surgical treatment of rectal cancer and to examine the outcome of postoperative treatment with sildenafil . Methods A prospect i ve study was performed in patients who underwent attempted curative total mesorectal excision ( TME ) for low rectal cancers .  Sexual function scores were determined by question naire preoperatively and at 3 and 12 months postoperatively . Outcomes were examined in patients who were sexually active preoperatively . Results From 2000 to 2007 , 207 patients underwent TME at our institution , of whom 49 ( 24 % ) were sexually active preoperatively .  Erectile dysfunction and ejaculatory problems were present in 80 % and 82 % , respectively of the 49 patients at 3 months postoperatively , and in 76 % and 67 % , respectively at 12 months . Lateral lymph node dissection was a strong risk factor for postoperative sexual dysfunction . The impotency rate was 37 % and 47 % of patients were unable to ejaculate . Sildenafil was administered to 16 patients who requested the drug during follow-up , and sexual dysfunction was improved in 11 of these patients ( 69 % ) . ConclusionS exual dysfunction occurs frequently after rectal cancer treatment and is mainly caused by surgical damage in lateral lymph node dissection . Sildenafil may be effective for the treatment of sexual dysfunction Diagnosis is a critical component of health care , and clinicians , policymakers , and patients routinely face a range of questions regarding diagnostic tests . They want to know whether testing improves outcome ; what test to use , purchase , or recommend in practice guidelines ; and how to interpret test results . Well- design ed  diagnostic test accuracy studies can help in making these decisions , provided that they transparently and fully report their participants , tests , methods , and results as facilitated , for example , by the STARD ( St and ards for Reporting of Diagnostic Accuracy ) statement ( 1 ) . That 25-item checklist was published in many journals and is now adopted by more than 200 scientific journals worldwide . As in other areas of science , systematic review s and meta- analysis of accuracy studies can be used to obtain more precise estimates when small studies addressing the same test and patients in the same setting are available . Review s can also be useful to establish whether and how scientific findings vary by particular subgroups , and may provide summary estimates with a stronger generalizability than estimates from a single study . Systematic review s may help identify the risk for bias that may be present in the original studies and can be used to address questions that were not directly considered in the primary studies , such as comparisons between tests . The Cochrane Collaboration is the largest international organization preparing , maintaining , and promoting systematic review s to help people make well-informed decisions about health care ( 2 ) . The Collaboration decided in 2003 to make preparations for including systematic review s of diagnostic test accuracy in their Cochrane Data base of Systematic Review s. To enable this , a working group ( Appendix ) . was formed to develop methodology , software , and a h and book The first diagnostic test accuracy review was published in the Cochrane Data base in October 2008 . In this paper , we review recent method ological developments concerning problem formulation , location of literature , quality assessment , and meta- analysis of diagnostic accuracy studies by using our experience from the work on the Cochrane H and book . The information presented here is based on the recent literature and up date s previously published guidelines by Irwig and colleagues ( 3 ) . Definition of the Objectives of the Review Diagnostic test accuracy refers to the ability of a test to distinguish between patients with disease ( or more generally , a specified target condition ) and those without . In a study of test accuracy , the results of the test under evaluation , the index test , are compared with those of the reference st and ard determined in the same patients . The reference st and ard is an agreed-on and accurate method for identifying patients who have the target condition . Test results are typically categorized as positive or negative for the target condition . By using such binary test outcomes , the accuracy is most often expressed as the test 's sensitivity ( the proportion of patients with positive results on the reference st and ard that are also positive on the index test ) and specificity ( the proportion of patients with negative results on the reference st and ard that are also negative on the index test ) . Other measures have been proposed and are in use ( 46 ) . It has long been recognized that test accuracy is not a fixed property of a test . It can vary between patient subgroups , with their spectrum of disease , with the clinical setting , or with the test interpreters and may depend on the results of previous testing . For this reason , inclusion of these elements in the study question is essential . In order to make a policy decision to promote use of a new index test , evidence is required that using the new test increases test accuracy over other testing options , including current practice , or that the new test has equivalent accuracy but offers other advantages ( 79 ) . As with the evaluation of interventions , systematic review s need to include comparative analyses between alternative testing strategies and should not focus solely on evaluating the performance of a test in isolation . In relation to the existing situation , 3 possible roles for a new test can be defined : replacement , triage , and add-on ( 7 ) . If a new test is to replace an existing test , then comparing the accuracy of both tests on the same population and with the same reference st and ard provides the most direct evidence . In triage , the new test is used before the existing test or testing pathway , and only patients with a particular result on the triage test continue the testing pathway . When a test is needed to rule out disease in patients who then need no further testing , a test that gives a minimal proportion of falsenegative results and thus a relatively high sensitivity should be used . Triage tests may be less accurate than existing ones , but they have other advantages , such as simplicity or low cost . A third possible role of a new test is add-on . The new test is then positioned after the existing testing pathway to identify false-positive or false-negative results after the existing pathway . The review should provide data to assess the incremental change in accuracy made by adding the new test . An example of a replacement question can be found in a systematic review of the diagnostic accuracy of urinary markers for primary bladder cancer ( 10 ) . Clinicians may use cytology to triage patients before they undergo invasive cystoscopy  , the reference st and ard for bladder cancer . Because cytology combines high specificity with low sensitivity ( 11 ) , the goal of the review was to identify a tumor marker with sufficient accuracy to either replace cytology or be used in addition to cytology . For a marker to replace cytology , it has to achieve equally high specificity with improved sensitivity . New markers that are sensitive but not specific may have roles as adjuncts to conventional testing . The review included studies in which the test under evaluation ( several different tumor markers and cytology ) was evaluated against cystoscopy or histopathology . Included studies compared 1 or more of the markers , cytology only , or a combination of markers and cytology . Although information on accuracy can help clinicians make decisions about tests , good diagnostic accuracy is a desirable but not sufficient condition for the effectiveness of a test ( 8) . To demonstrate that using a new test does more good than harm to patients tested , r and omized trials of test- and -treatment strategies and review s of such trials may be necessary . However , with the possible exception of screening , in most cases , such r and omized trials are not available and systematic review s of test accuracy may provide the most useful evidence available to guide clinical and health policy decision making and use as input for decision and cost-effectiveness analysis ( 12 ) . Identification and Selection of Studies Identifying test accuracy studies is more difficult than search ing for r and omized trials ( 13 ) . There is not a clear , unequivocal keyword or indexing term for an accuracy study in literature data bases comparable with the term r and omized , controlled trial . The Medical Subject Heading sensitivity and specificity may look suitable but is inconsistently applied in most electronic bibliographic data bases . Furthermore , data on diagnostic test accuracy may be hidden in studies that did not have test accuracy estimation as their primary objective . This complicates the efficient identification of diagnostic test accuracy studies in electronic data bases , such as MEDLINE . Until indexing systems properly code studies of test accuracy , search ing for them will remain challenging and may require additional manual search es , such as screening reference lists . In the development of a comprehensive search strategy , review authors can use search strings that refer to the test(s ) under evaluation , the target condition , and the patient description or a subset of these . For tests with a clear name that are used for a single purpose , search ing for publications in which those tests are mentioned may suffice . For other review s , adding the patient description may be necessary , although this is also often poorly indexed . A search strategy in MEDLINE should contain both Medical Subject Headings and free text words . A search strategy for articles about tests for bladder cancer , for example , should include as many synonyms for bladder cancer as possible in the search strategy , including neoplasm , carcinoma , transitional cell , and hematuria . Several method ological electronic search filters for diagnostic test accuracy studies have been developed , each attempting to restrict the search to articles that are most likely to be test accuracy studies ( 1316 ) . These filters rely on indexing terms for research methodology and text words used in reporting results , but they often miss relevant studies and are unlikely to decrease the number of articles one needs to screen . Therefore , they are not recommended for systematic review s ( 17 , 18 ) . The incremental value of search ing in language s other than English and in the gray literature has not yet been fully investigated . In systematic review s of intervention studies , publication bias is an important and well-studied form of bias in which the decision to report and publish studies is linked to their findings . For clinical trials , the magnitude and determinants of publication bias have been identified by tracing the publication history of cohorts of trials review ed by ethics committees and research boards ( 19 ) . A consistent observation has been that studies with significant results are more likely to be published than studies with nonsignificant findings ( 19 ) . Investigating publication bias for diagnostic tests is problematic , because many studies are done without ethical review or study registration ; therefore , identification of cohorts of studies from registration to final publication status BACKGROUND We conducted a r and omized controlled trial ( JCOG0212 ) to determine whether the outcome of mesorectal excision ( ME ) alone for rectal cancer is not inferior to that of ME with lateral lymph node dissection ( LLND ) . The present study focused on male sexual dysfunction after surgery . METHODOLOGY Eligibility criteria included clinical stage II/III rectal cancer , the lower margin of the lesion below the peritoneal reflection , the absence of lateral pelvic lymph node enlargement , and no preoperative radiotherapy .  After confirmation of R0 resection by ME , patients were intraoperatively r and 
    Output:
    
Conclusions Magnetic resonance imaging was useful to diagnose lateral lymph node metastasis in rectal cancer , especially due to high specificity