title: Extramural depth of rectal cancer tumor invasion at thin-section MRI: predicting treatment response to neoadjuvant chemoradiation.
abstract: OBJECTIVE
  To assess whether the maximal extramural depth (EMD) of T3 tumor spread on magnetic resonance imaging(MRI) correlates with tumor response parameters and whether it can predict tumor response to neoadjuvant chemoradiation.
  
  
  METHODS
  111 rectal cancer patients with American Joint Committee on Cancer (AJCC) T3 tumors underwent MRI staging before neoadjuvant chemoradiotherapy were included. Tumor EMD was measured as mm tumor beyond the muscular and compared between the following groups by Kruskal-Wallis test: pathological complete response(pCR) versus nonpCR, good regression versus poor regression, downstage versus nondownstage.
  
  
  RESULTS
  The final study population consisted of the 111 patients (79 male, 32 female). Median age was 56 years (range, 23-75 years). The EMD was significantly higher in nonpCR patients (7.8 ± 3.2 mm) than in pCR patients(6.1 ± 1.8 mm) (p = 0.033). According to good regression (tumor regression grade(TRG) 0-1 vs. TRG 2-3) and downstaging (ypStage 0-I vs. ypStage II-III), the difference was not significant. Receiver operating characteristic curve analysis revealed a good value for the area under the curve (0.775) and the cutoff value for EMD to predict pCR was 5.6 mm. Compared with patients with a EMD ≥ 5 mm, more patients with EMD <5 mm showed pCR (p = 0.019), while there was no correlation between EMD and good regression or downstaged.
  
  
  CONCLUSIONS
  EMD value obtained on initial staging MRI may serve as an imaging biomarker which predicts patients that have an incomplete response pathological response after standard neoadjuvant therapy.
authors: Department of Radiology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors: Tong
authors: T
authors: Tong
authors: Department of Radiology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors: Yiqun
authors: Y
authors: Sun
authors: Department of Colorectal Surgery, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors: Sanjun
authors: S
authors: Cai
authors: Department of Radiotherapy, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors: Zhen
authors: Z
authors: Zhang
authors: Department of Radiology, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors: Yajia
authors: Y
authors: Gu
mesh_terms: D000328:Adult; D000368:Aged; D019540:Area Under Curve; D002277:Carcinoma / Q000473:pathology* / Q000628:therapy*; D059186:Chemoradiotherapy, Adjuvant; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D012372:ROC Curve; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D012074:Remission Induction; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
keywords: MRI; depth of invasion; neoadjuvant therapy; rectal cancer