***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 If treatment of the axilla is indicated in patients with breast cancer who have a positive sentinel node , axillary lymph node dissection is the present st and ard . Although axillary lymph node dissection provides excellent regional control , it is associated with harmful side-effects . We aim ed to assess whether axillary radiotherapy provides comparable regional control with fewer side-effects . METHODS Patients with T1 - 2 primary breast cancer and no palpable lymphadenopathy were enrolled in the r and omised , multicentre , open-label , phase 3 non-inferiority EORTC 10981 - 22023 AMAROS trial . Patients were r and omly assigned ( 1:1 ) by a computer-generated allocation schedule to receive either axillary lymph node dissection or axillary radiotherapy in case of a positive sentinel node , stratified by institution . The primary endpoint was non-inferiority of 5-year axillary recurrence , considered to be not more than 4 % for the axillary radiotherapy group compared with an expected 2 % in the axillary lymph node dissection group . Analyses were by intention to treat and per protocol . The AMAROS trial is registered with Clinical Trials.gov , number NCT00014612 . FINDINGS Between Feb 19 , 2001 , and April 29 , 2010 , 4823 patients were enrolled at 34 centres from nine European countries , of whom 4806 were eligible for r and omisation . 2402 patients were r and omly assigned to receive  axillary lymph node dissection and 2404 to receive axillary radiotherapy . Of the 1425 patients with a positive sentinel node , 744 had been r and omly assigned to axillary lymph node dissection and 681 to axillary radiotherapy ; these patients constituted the intention-to-treat population . Median follow-up was 6·1 years ( IQR 4·1 - 8·0 ) for the patients with positive sentinel lymph nodes . In the axillary lymph node dissection group , 220 ( 33 % ) of 672 patients who underwent axillary lymph node dissection had additional positive nodes . Axillary recurrence occurred in four of 744 patients in the axillary lymph node dissection group and seven of 681 in the axillary radiotherapy group . 5-year axillary recurrence was 0·43 % ( 95 % CI 0·00 - 0·92 ) after axillary lymph node dissection versus 1·19 % ( 0·31 - 2·08 ) after axillary radiotherapy . The planned non-inferiority test was underpowered because of the low number of events . The one-sided 95 % CI for the underpowered non-inferiority test on the hazard ratio was 0·00 - 5·27 , with a non-inferiority margin of 2 . Lymphoedema in the ipsilateral arm was noted significantly more often after axillary lymph node dissection than after axillary radiotherapy at 1 year , 3 years , and 5 years . INTERPRETATION Axillary lymph node dissection and axillary radiotherapy after a positive sentinel node provide excellent and comparable axillary control for patients with T1 - 2 primary breast cancer and no palpable lymphadenopathy . Axillary radiotherapy results in significantly less morbidity . FUNDING EORTC Charitable Trust PURPOSE To compare the diagnostic accuracy of ultrasonographically (US)-guided fine-needle aspiration biopsy ( FNAB ) and core-needle biopsy ( CNB ) of the axillary lymph nodes ( LNs ) of patients with newly diagnosed invasive breast cancer . MATERIAL S AND METHODS This prospect i ve single-center study had institutional review board approval , and written informed consent was obtained . Between April 2011 and March 2012 , 178 consecutive patients ( 182 axillae ) were evaluated by using axillary US .  Sixty-six axillae fulfilled the inclusion criteria ( cortical thickness greater than 2 mm or abnormal morphologic characteristics ) , and patients with these axillae underwent  US-guided axillary LN biopsy . Both FNAB and CNB were obtained from the same suspicious LN . Patients with biopsy-proved metastasis underwent axillary clearance , and those with a negative biopsy underwent sentinel LN biopsy with completion axillary clearance if needed . Diagnostic performance was calculated separately for US , FNAB , and CNB . Statistical differences in sensitivities were evaluated by using the McNemar test . RESULTS From the total study population , 45.6 % ( 83 of 182 axillae ) had metastases . A total of 66 axillae underwent both FNAB and CNB . The sensitivity for US was 61.4 % ( 51 of 83 axillae ) , and specificity was 84.8 % ( 84 of 88 axillae ) . The sensitivities for FNAB and CNB were 72.5 % ( 37 of 51 axillae ) and 88.2 % ( 45 of 51 axillae ) , respectively ( P = .008 ) . Specificity for both was 100 % ( 15 of 15 axillae ) . The negative predictive value for FNAB was 81.7 % , and that for CNB was 91.2 % . The positive predictive value was 100 % for both methods . CONCLUSION When accurate preoperative staging of the axilla is needed in patients with newly diagnosed invasive breast cancer , CNB is more sensitive than FNAB CRA506 Background : Sentinel node biopsy ( SNB ) eliminates the need for axillary dissection ( ALND ) in patients whose sentinel node ( SN ) is tumor-free . However , completion ALND remains the gold st and ard for patients with a tumor-involved sentinel node . ALND achieves regional control , but its effect on survival remains controversial . The main objective of ACOSOG Z0011 was to compare outcomes of patients with hematoxylin and eosin ( H&E ) detected metastasis in SN managed with or without ALND and no axillary irradiation . METHODS Clinical ly node-negative patients who underwent SN biopsy and had 1 or 2 SN with metastases detected by H&E were r and omized to ALND or no further axillary specific treatment .  All patients were treated with lumpectomy and opposing tangential field irradiation . Adjuvant systemic therapy was at the discretion of their physicians . Overall survival ( OS ) , disease-free survival ( DFS ) , and locoregional control were evaluated . RESULTS 446 patients were r and omized to SNB alone and 445 to SNB plus ALND . Patients treated with SNB alone were similar to those treated with SNB + ALND with respect to age , tumor size , Bloom-Richardson score , estrogen receptor status , adjuvant systemic therapy , tumor type , and T stage . Patients r and omized to SNB alone had a median of two lymph nodes removed whereas patients r and omized to ALND had a median of 17 lymph nodes removed . 17.6 % of ALND patients had 3 or more involved nodes compared to 5.0 % of SNB patients ( p < 0.001 ) . Median follow-up is 6.2 years . 5-year in breast recurrence after ALND was 3.7 % compared to 2.1 % for SNB ( p = 0.16 ) while 5-year nodal recurrence was 0.6 % compared to 1.3 % ( p = 0.44 ) respectively . The five-year OS for patients undergoing SNB + ALND is 91.9 % compared to 92.5 % for SNB alone ( p = 0.24 ) , and DFS is 82.2 % compared to 83.8 % respectively ( p = 0.13 ) . CONCLUSIONS Despite the widely held belief that ALND improves survival , no significant difference was recognized by this study of SN node-positive women . Although the study closed early because of low accrual/event rate , it is the largest phase III study of ALND for node-positive women , and it demonstrates no trend toward clinical benefit of ALND for patients with limited nodal disease . [ Table : see text ] Ultrasound ( US ) is more sensitive than physical examination alone in determining axillary lymph node involvement during preliminary staging of breast carcinoma . Due to occasional overlap of sonographic features of benign and indeterminate lymph nodes , fine‐needle aspiration ( FNA ) of sonographically indeterminate/suspicious lymph nodes can provide a more definitive diagnosis than US alone . This study was undertaken to determine the diagnostic accuracy of US‐guided FNA of indeterminate/suspicious/metastatic‐appearing axillary lymph nodes during the initial staging of breast carcinoma 96 Background : The sensitivity and specificity of FNAB and CNB performed in suspicious axillary LNs have ranged from 56 % to 86 % and from 91 % to 100 % , because FNAB and CNB are operator- and institution-dependent procedures . In addition , previous studies concerning the diagnostic accuracy of these procedures have reported results from only FNAB or CNB . So , the purpose of this study was to determine the diagnostic accuracy of axillary US and compare that of US-guided FNAB with CNB for axillary staging in the same breast cancer population . METHODS Of 220 breast cancer patients who underwent preoperative or prechemotherapy axillary US for axillary staging , 52 patients who underwent US-guided FNAB and CNB of cortical thickening and /or compressed hilum of lymph nodes on US were prospect ively enrolled . US and FNAB/CNB findings were compared with final pathology from sentinel lymph node biopsy or axillary lymph node dissection . RESULTS Forty-eight patients met the final study criteria ; we excluded 4 who had received primary systemic chemotherapy and showed negative FNAB/CNB results with negative final post-operative pathology . Positive predictive value ( PPV ) of axillary US was 54 % . The sensitivity and specificity of FNAB were 73 % and 100 % , and those of CNB were 77 % and 100 % . Results did not significantly differ between US-guided CNB and FNAB . The complication rates of FNAB and CNB were 4 % , and FNAB and CNB cost $ 180 and $ 350 , respectively . CONCLUSIONS Both US-guided CNB and FNAB were useful for axillary staging in breast cancer patients with high sensitivity . However , FNAB is recommended based on the advantages of low cost and minimal invasiveness A quantitative systematic review , or meta- analysis , uses statistical methods to combine the results of multiple studies . Meta-analyses have been done for systematic review s of therapeutic trials , diagnostic test evaluations , and epidemiologic studies . Although the statistical methods involved may at first appear to be mathematically complex , their purpose is simple : They are trying to answer four basic questions . Are the results of the different studies similar ? To the extent that they are similar , what is the best overall estimate ? How precise and robust is this estimate ? Finally , can dissimilarities be explained ? This article provides some guidance in underst and ing the key technical aspects of the quantitative approach to these questions . We have avoided using equations and statistical notations ; interested readers will find implementations of the described methods in the listed references . We focus here on the quantitative synthesis of reports of r and omized , controlled , therapeutic trials because far more meta-analyses on therapeutic studies than on other types of studies have been published . For practical reasons , we present a stepwise description of the tasks that are performed when statistical methods are used to combine data . These tasks are 1 ) deciding whether to combine data and defining what to combine , 2 ) evaluating the statistical heterogeneity of the data , 3 ) estimating a common effect , 4 ) exploring and explaining heterogeneity , 5 ) assessing the potential for bias , and 6 ) presenting the results . Deciding Whether To Combine Data and Defining What To Combine By the time one performs a quantitative synthesis , certain decisions should already have been made about the formulation of the question and the selection of included studies . These topics were discussed in two previous articles in this series [ 1 , 2 ] . Statistical tests can not compensate for lack of common sense , clinical acumen , and biological plausibility in the design of the protocol of a meta- analysis . Thus , a reader of a systematic review should always address these issues before evaluating the statistical methods that have been used and the results that have been generated . Combining poor- quality data , overly biased data , or data that do not make sense can easily produce unreliable results . The data to be combined in a meta- analysis are usually either binary or continuous . Binary data involve a yes/no categorization ( for example , death or survival ) . Continuous data take a range of values ( for example , change in diastolic blood pressure after antihypertensive treatment , measured in mm Hg ) . When one is comparing groups of patients , binary data can be summarized by using several measures of treatment effect that were discussed earlier in this series [ 3 ] . These measures include the risk ratio ; the odds ratio ; the risk difference ; and , when study duration is important , the incidence rate . Another useful clinical measure , the number needed to treat ( NNT ) , is derived from the inverse of the risk difference [ 3 ] . Treatment effect measures , such as the risk ratio and the odds ratio , provide an estimate of the relative efficacy of an intervention , whereas the risk difference describes the intervention 's absolute benefit . The various measures of treatment effect offer complementary information , and all should be examined [ 4 ] . Continuous data 
    Output:
    
US-CNB is a superior diagnostic technique to US-FNA for axillary staging in breast cancer