***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 design ed American College of Surgeons Oncology Group ( ACOSOG ) Z6041 , a prospect i ve , multicenter , single-arm , phase II trial to assess the efficacy and safety of neoadjuvant chemoradiation ( CRT ) and local excision ( LE ) for T2N0 rectal cancer . Here , we report tumor response , CRT-related toxicity , and perioperative complications ( PCs ) . Methods Clinical ly staged T2N0 rectal cancer patients were treated with capecitabine and oxaliplatin during radiation followed by LE . Because of toxicity , capecitabine and radiation doses were reduced . LE was performed 6 weeks after CRT . Patients were evaluated for clinical and pathologic response . CRT-related complications and PCs were recorded . Results Ninety patients were accrued ; 6 received non protocol treatment . The remaining 84 were 65 % male ; median age 63 years ; 83 % Eastern Cooperative Oncology Group performance score 0 ; 92 % white ; mean tumor size 2.9 cm ; and average distance from anal verge 5.1 cm . Five patients were considered ineligible . Therapy was completed per protocol in 79 patients , but two patients did not undergo LE . Among 77 eligible patients who underwent LE  , 34 patients achieved a pathologic complete response ( 44 % ) and 49 ( 64 % ) tumors were downstaged ( ypT0–1 ) , but 4 patients ( 5 % ) had ypT3 tumors . Five LE specimens contained lymph nodes ; one T3 tumor had a positive node . All but one patient had negative margins . Thirty-three ( 39 % ) of 84 patients developed CRT-related grade ≥3 complications . Rectal pain was the most common PC . Conclusions CRT before LE for T2N0 tumors results in a high pathologic complete response rate and negative resection margins . However , complications during CRT and after LE are high . The true efficacy of this approach will ultimately be assessed by the long-term oncologic outcomes Background : Retrospective single-center studies have shown that diffusion-weighted magnetic resonance imaging ( DWI ) is promising for identification of patients with rectal cancer with a complete tumor response after neoadjuvant chemoradiotherapy ( CRT )  , using certain volumetric thresholds . Objective : This study aims to vali date the diagnostic value of these volume thresholds in a larger , independent , and bi-institutional patient cohort . Methods : A total of 112 patients with locally advanced rectal cancer ( 2 centers ) treated with a long course of CRT were enrolled . Patients underwent st and ard T2W-magnetic resonance imaging and DWI , both pre- and post-CRT . Two experienced readers independently determined pre-CRT and post-CRT tumor volumes ( cm3 ) on T2W-magnetic resonance image and diffusion-weighted magnetic resonance image by means of freeh and tumor delineation . Tumor volume reduction rates ( & Dgr;volume ) were calculated . Previously determined T2W and DWI threshold values for prevolume , postvolume , and & Dgr;volume were tested to “ prospect ively ” assess their respective diagnostic value in discriminating patients with a complete tumor response from patients with residual tumor . Results : Twenty patients had a complete response . Using the average measurements between the 2 readers , areas under the curve for the pre-/post-/&Dgr;volumes was 0.73/0.82/0.78 for T2W-magnetic resonance imaging and 0.77/0.92/0.86 for DWI , respectively . For T2W-volumetry , sensitivity and specificity using the predefined volume thresholds were 55 % and 74 % for pre- , 60 % and 89 % for post- , and 60 % and 86 % for & Dgr;volume . For DWI volumetry , sensitivity and specificity were 65 % and 76 % for pre- , 70 % and 98 % for post- , and 70 % and 93 % for & Dgr;volume . Conclusions : Previously established DWI volume thresholds can be reproduced with good results . Post-CRT DWI volumetry offers the best results for the detection of patients with a complete response after CRT with an area under the curve of 0.92 , sensitivity of 70 % , and specificity of 98 % BACKGROUND AND STUDY AIMS The aim of this study was to assess whether preoperative endorectal ultrasound ( ERUS ) is able to predict histological infiltration of the external anal sphincter or the levator ani muscle in patients with a lower-third rectal neoplasm and so the possibility of treatment by sphincter-saving surgery . PATIENTS AND METHODS Between May 1996 and May 2003 , 66 patients with a lower-third rectal neoplasm that was staged as uT2 or greater were entered into a prospect i ve evaluation of ERUS . All patients underwent neoadjuvant treatment before surgery . RESULTS The first ERUS ( ERUS 1 ) was performed before neoadjuvant treatment ; the second ERUS ( ERUS 2 ) was performed between the end of the radiotherapy and the surgery . An abdominoperineal resection was performed mainly when the lower extent of the tumor was within 3.5 cm from the anal verge ( P = 0.011 ) , but no correlation was observed between the lateral clearance determined by ERUS 1 and the histological clearance ( P = 0.091 ) . After neoadjuvant treatment , the ERUS 2 lateral clearance was significantly correlated with the type of surgery ( P = 0.003 ) and the histological clearance ( P < 0.001 ) . With regard to the performance of ERUS 2 for predicting histological infiltration of the external anal sphincter or the levator ani muscle , the sensitivity was 100 % , the negative predictive value was 100 % , the specificity was 87 % , and the positive predictive value was 53 % . In a multivariate analysis , the histological clearance and tumor T stage were statistically correlated with disease-free survival ( P = 0.035 and P = 0.05 , respectively ) . CONCLUSIONS ERUS could help oncologists and surgeons in the management of patients with lower rectal carcinomas . Moreover , ERUS is able to predict lateral histological clearance after neoadjuvant treatment BACKGROUND To date , the role of endoscopic ultrasound ( EUS ) in restaging locally advanced rectal cancer ( LARC ) after neoadjuvant chemoradiotherapy ( NAT ) have not been thoroughly investigated . AIM To evaluate accuracy and clinical usefulness of EUS for both staging and restaging LARC . METHODS According to EUS staging , patients with LARC were enrolled in the study . Those who underwent surgery directly represented a control group useful for evaluating the accuracy of EUS in staging LARC . In the study group , EUS was repeated seven weeks after NAT , before surgery . The results of EUS were compared with the corresponding pTN stages . RESULTS From 2000 to 2006 , 212 consecutive patients with RC underwent EUS staging . Among them  EUS diagnosed 162 LARC ( M/F = 93/69 ; mean age : 60 years [ range 40 - 80 ] ) . The final study group included 85 patients with LARC .  EUS restaging had an overall accuracy of 61 % and 59 % for T and N-stage , respectively . In the control group , the accuracy of EUS in staging LARC was 86 % and 58 % for T and N-stage , respectively . CONCLUSION EUS accurately stages LARC and enables appropriate decision-making , with selection of those patients who need NAT . On the other h and , EUS restaging of LARC after NAT has low accuracy and should not be used in clinical practice BACKGROUND Postoperative chemoradiotherapy is the recommended st and ard therapy for patients with locally advanced rectal cancer . In recent years , encouraging results with preoperative radiotherapy have been reported . We compared preoperative chemoradiotherapy with postoperative chemoradiotherapy for locally advanced rectal cancer . METHODS We r and omly assigned patients with clinical stage T3 or T4 or node-positive disease to receive either  preoperative or postoperative chemoradiotherapy . The preoperative treatment consisted of 5040 cGy delivered in fractions of 180 cGy per day , five days per week , and fluorouracil , given in a 120-hour continuous intravenous infusion at a dose of 1000 mg per square meter of body-surface area per day during the first and fifth weeks of radiotherapy . Surgery was performed six weeks after the completion of chemoradiotherapy . One month after surgery , four five-day cycles of fluorouracil ( 500 mg per square meter per day ) were given . Chemoradiotherapy was identical in the postoperative-treatment group , except for the delivery of a boost of 540 cGy . The primary end point was overall survival . RESULTS Four hundred twenty-one patients were r and omly assigned to receive preoperative chemoradiotherapy  and 402 patients to receive postoperative chemoradiotherapy . The overall five-year survival rates were 76 percent and 74 percent , respectively ( P=0.80 ) . The five-year cumulative incidence of local relapse was 6 percent for patients assigned to preoperative chemoradiotherapy and 13 percent in the postoperative-treatment group ( P=0.006 ) . Grade 3 or 4 acute toxic effects occurred in 27 percent of the patients in the preoperative-treatment group , as compared with 40 percent of the patients in the postoperative-treatment group ( P=0.001 ) ; the corresponding rates of long-term toxic effects were 14 percent and 24 percent , respectively ( P=0.01 ) . CONCLUSIONS Preoperative chemoradiotherapy , as compared with postoperative chemoradiotherapy , improved local control and was associated with reduced toxicity but did not improve overall survival Objectives To evaluate the performance of diffusion-weighted MRI ( DWI ) in addition to T2-weighted ( T2W ) MRI for nodal restaging after chemoradiation in rectal cancer . Methods Thirty patients underwent chemoradiation followed by MRI ( 1.5 T ) and surgery .  Imaging consisted of T2W-MRI and DWI ( b0 , 500 , 1000 ) . On T2W-MRI , nodes were scored as benign/malignant by two independent readers ( R1 , R2 ) . Mean apparent diffusion coefficient ( ADC ) was measured for each node . Diagnostic performance was compared for T2W-MRI , ADC and T2W+ADC , using a per lesion histological validation . Results ADC was higher for the malignant nodes ( 1.43 ± 0.38 vs 1.19 ± 0.27 * 10−3 mm2/s , p < 0.001 ) . Area under the ROC curve/sensitivity/specificity were 0.88/65%/93 % ( R1 ) and 0.95/71%/91 % ( R2 ) using T2W-MRI ; 0.66/53%/82 % using ADC ( mean of two readers ) ; and 0.91/56%/98 % ( R1 ) and 0.96/56%/99 % ( R2 ) using T2W+ADC . There was no significant difference between T2W-MRI and T2W+ADC . Interobserver reproducibility was good for T2W-MRI ( κ0.73 ) and ADC ( intraclass correlation coefficient 0.77 ) . Conclusions After chemoradiation , ADC measurements may have potential for nodal characterisation , but DWI on its own is not reliable . Addition of DWI to T2W-MRI does not improve accuracy and T2W-MRI is already sufficiently accurate PURPOSE This study was design ed to evaluate prospect ively magnetic resonance imaging for the prediction of the circumferential resection margin in rectal cancer to identify in which patient magnetic resonance imaging could accurately assess the circumferential resection margin before surgery and in which patients it could not . METHODS During a 17-month period , a preoperative magnetic resonance imaging for the assessment of circumferential resection margin was obtained prospect ively in 38 patients with mid or low rectal cancer . The agreement of magnetic resonance imaging and pathologic examination for assessment of circumferential resection margin was analyzed . RESULTS Overall , magnetic resonance imaging agreed with histologic examination of the circumferential resection margin assessment in 28 patients ( 73 percent ; κ = 0.47 ) . In all cases of disagreement between magnetic resonance imaging and pathology , magnetic resonance imaging overestimated the circumferential resection margin involvement . For the 11 patients with mid rectal cancer  , circumferential resection margin was well predicted by magnetic resonance imaging in all cases ( κ = 1 ) . For 27 patients with low rectal tumor , overall agreement between magnetic resonance imaging and histologic assessment was 63 percent ( κ = 0.35 ) . Agreement was 22 percent ( κ = 0.03 ) for the 9 patients with low anterior and 83 percent ( κ = 0.67 ) for the 18 patients with low posterior rectal tumor . Univariate analysis revealed that only low and anterior rectal tumor was risk factor of overestimation of the circumferential resection margin by magnetic resonance imaging . CONCLUSIONS Although magnetic resonance imaging remains the best imaging tool for the preoperative assessment of the circumferential resection margin in patients with rectal cancer , it can overestimate the circumferential resection margin involvement in low and anterior tumor with 
    Output:
    
Restaging MRI is accurate at excluding circumferential resection margin involvement .
The heterogeneity amongst restaging studies is high , limiting conclusive findings regarding their accuracies .
The accuracy of restaging imaging is different for different pathological T stages and highest for T3 tumours .
Morphological assessment of T- or N-stage by MRI or ERUS is currently not accurate or consistent enough for clinical application .
Restaging MRI appears to have a role in excluding circumferential resection margin involvement