title: Tumor volume changes assessed by three-dimensional magnetic resonance volumetry in rectal cancer patients after preoperative chemoradiation: the impact of the volume reduction ratio on the prediction of pathologic complete response.
abstract: OBJECTIVE
  The aim of this study was to determine the correlation between tumor volume changes assessed by three-dimensional (3D) magnetic resonance (MR) volumetry and the histopathologic tumor response in rectal cancer patients undergoing preoperative chemoradiation therapy (CRT).
  
  
  METHODS
  A total of 84 patients who underwent preoperative CRT followed by radical surgery were prospectively enrolled in the study. The post-treatment tumor volume and tumor volume reduction ratio (% decrease ratio), as shown by 3D MR volumetry, were compared with the histopathologic response, as shown by T and N downstaging and the tumor regression grade (TRG).
  
  
  RESULTS
  There were no significant differences in the post-treatment tumor volume and the volume reduction ratio shown by 3D MR volumetry with respect to T and N downstaging and the tumor regression grade. In a multivariate analysis, the tumor volume reduction ratio was not significantly associated with T and N downstaging. The volume reduction ratio (>75%, p = 0.01) and the pretreatment carcinoembryonic antigen level (< or =3 ng/ml, p = 0.01), but not the post-treatment volume shown by 3D MR (< or = 5 ml), were, however, significantly associated with an increased pathologic complete response rate.
  
  
  CONCLUSIONS
  More than 75% of the tumor volume reduction ratios were significantly associated with a high pathologic complete response rate. Therefore, limited treatment options such as local excision or simple observation might be considered after preoperative CRT in this patient population.
authors: Department of Surgery, Yonsei University Health System, Yonsei University College of Medicine, Seoul 120-752, South Korea.
authors: Jeong Hyun
authors: JH
authors: Kang
authors: Young Chul
authors: YC
authors: Kim
authors: Hyunki
authors: H
authors: Kim
authors: Young Wan
authors: YW
authors: Kim
authors: Hyuk
authors: H
authors: Hur
authors: Jin Soo
authors: JS
authors: Kim
authors: Byung Soh
authors: BS
authors: Min
authors: Hogeun
authors: H
authors: Kim
authors: Joon Seok
authors: JS
authors: Lim
authors: Jinsil
authors: J
authors: Seong
authors: Ki Chang
authors: KC
authors: Keum
authors: Nam Kyu
authors: NK
authors: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003131:Combined Modality Therapy / Q000379:methods; D051517:Digital Rectal Examination; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies; D020266:Radiotherapy, Conformal; D012004:Rectal Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000601:surgery; D012074:Remission Induction; D047368:Tumor Burden