title: Relationship between histologic response and the degree of tumor shrinkage after chemoradiotherapy in patients with locally advanced rectal cancer.
abstract: BACKGROUND
  Preoperative chemoradiotherapy (CRT) significantly decreases local recurrence in advanced rectal cancer. We studied whether the degree of tumor shrinkage can be used as a predictor of histologic response.
  
  
  METHODS
  The subjects were 114 patients with locally advanced rectal cancer who underwent total mesorectal excision after receiving radiotherapy combined with uracil/tegafur (UFT) or S-1. The degree of tumor shrinkage based on barium enema examination and magnetic resonance imaging (MRI) were assessed before CRT and immediately before surgery.
  
  
  RESULTS
  A histologic complete response (ypCR), histologic marked regression, T and N downstaging were associated with significantly higher tumor-shrinkage rates on barium enema (P < 0.01, P < 0.01, P < 0.01, and P < 0.01, respectively) as well as on MRI (P < 0.01, P < 0.01, P < 0.01, and P = 0.01, respectively). On multivariate analysis, ypCR and histologic marked regression were significantly related only to tumor-shrinkage rates on barium enema (P < 0.01 and P < 0.01, respectively), and were not related to tumor-shrinkage rates on MRI.
  
  
  CONCLUSIONS
  The degree of tumor shrinkage is closely related to the final histologic response. Two-dimensionally evaluated tumor-shrinkage rates based on barium enema are adequate for the prediction of histologic response.
authors.affiliation: Departments of Surgery, Tokai University School of Medicine, Kanagawa, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Suzuki
authors.forename: Sotaro
authors.initials: S
authors.lastname: Sadahiro
authors.forename: Akira
authors.initials: A
authors.lastname: Tanaka
authors.forename: Kazutake
authors.initials: K
authors.lastname: Okada
authors.forename: Gota
authors.initials: G
authors.lastname: Saito
authors.forename: Akemi
authors.initials: A
authors.lastname: Kamijo
authors.forename: Takeshi
authors.initials: T
authors.lastname: Akiba
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kawada
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059248:Chemoradiotherapy; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D014057:Tomography, X-Ray Computed
keywords: chemoradiotherapy; histologic regression; rectal cancer; tumor shrinkage