title: Computed tomography with histological correlation for evaluating tumor regression of rectal carcinoma after preoperative chemoradiation therapy.
abstract: OBJECTIVE
  Preoperative chemoradiation therapy (CRT) is standard procedure for locally advanced rectal cancer. The correlation of tumor response evaluated using CT according to response evaluation criteria in solid tumors (RECIST) with the histo-logical tumor regression grade (TRG) is not well-documented.
  
  
  METHODS
  Ninety-one patients with rectal cancer underwent CT examinations before and after preoperative CRT and following surgery. Clinical tumor staging and tumor response assessed according to RECIST were done on paired CT scans. Pathological tumor staging and TRGs were reviewed in resected specimens.Post-CRT CT findings and histological findings were compared. Survival analysis for 73 patients was done.
  
  
  RESULTS
  TRG was positively correlated with the CT-assessed tumor response (r=0.276, p=0.009). Thickened fibrotic areas and muscle disarray caused by fibrosis were more frequently seen in cases of patients over-diagnosed as having residual tumors. The ycT status was positively correlated with ypT status (r=0.44, p<0.001;accuracy=61.5%). Downstaging of cT status was cor-related with a lower TRG (p=0.001).
  
  
  CONCLUSIONS
  Fibrosis emerges after neoadjuvant therapy and is usual-ly accompanied by tumor reduction on CT scans of rec-tal cancer patients following preoperative CRT. There-fore, tumor response assessed using CT according to RECIST may serve as a supplementary tool for preoperative planning other than tumor restaging.
authors.affiliation: Department of Pathology, National Cheng Kung University Hospital, Tainan, Taiwan.
authors.forename: Chung-Ta
authors.initials: CT
authors.lastname: Lee
authors.forename: Nan-Haw
authors.initials: NH
authors.lastname: Chow
authors.forename: Yi-Sheng
authors.initials: YS
authors.lastname: Liu
authors.forename: Shao-Chieh
authors.initials: SC
authors.lastname: Lin
authors.forename: Peng-Chan
authors.initials: PC
authors.lastname: Lin
authors.forename: Yuan-Hua
authors.initials: YH
authors.lastname: Wu
authors.forename: Jenq-Chang
authors.initials: JC
authors.lastname: Lee
authors.forename: Hong-Ming
authors.initials: HM
authors.lastname: Tsai
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D001706:Biopsy; D059186:Chemoradiotherapy, Adjuvant / Q000009:adverse effects / Q000401:mortality; D016009:Chi-Square Distribution; D013505:Digestive System Surgical Procedures / Q000009:adverse effects / Q000401:mortality; D051517:Digital Rectal Examination; D018572:Disease-Free Survival; D005260:Female; D005355:Fibrosis; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000009:adverse effects / Q000401:mortality; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011300:Preoperative Care; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D012189:Retrospective Studies; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome