title: Tumor volume reduction rate after preoperative chemoradiotherapy as a prognostic factor in locally advanced rectal cancer.
abstract: OBJECTIVE
  To investigate the prognostic significance of tumor volume reduction rate (TVRR) after preoperative chemoradiotherapy (CRT) in locally advanced rectal cancer (LARC).
  
  
  METHODS
  In total, 430 primary LARC (cT3-4) patients who were treated with preoperative CRT and curative radical surgery between May 2002 and March 2008 were analyzed retrospectively. Pre- and post-CRT tumor volumes were measured using three-dimensional region-of-interest MR volumetry. Tumor volume reduction rate was determined using the equation TVRR (%) = (pre-CRT tumor volume--post-CRT tumor volume) × 100/pre-CRT tumor volume. The median follow-up period was 64 months (range, 27-99 months) for survivors. Endpoints were disease-free survival (DFS) and overall survival (OS).
  
  
  RESULTS
  The median TVRR was 70.2% (mean, 64.7% ± 22.6%; range, 0-100%). Downstaging (ypT0-2N0M0) occurred in 183 patients (42.6%). The 5-year DFS and OS rates were 77.7% and 86.3%, respectively. In the analysis that included pre-CRT and post-CRT tumor volumes and TVRR as continuous variables, only TVRR was an independent prognostic factor. Tumor volume reduction rate was categorized according to a cutoff value of 45% and included with clinicopathologic factors in the multivariate analysis; ypN status, circumferential resection margin, and TVRR were significant prognostic factors for both DFS and OS.
  
  
  CONCLUSIONS
  Tumor volume reduction rate was a significant prognostic factor in LARC patients receiving preoperative CRT. Tumor volume reduction rate data may be useful for tailoring surgery and postoperative adjuvant therapy after preoperative CRT.
authors: Center for Colorectal Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors: Seung-Gu
authors: SG
authors: Yeo
authors: Dae Yong
authors: DY
authors: Kim
authors: Ji Won
authors: JW
authors: Park
authors: Jae Hwan
authors: JH
authors: Oh
authors: Sun Young
authors: SY
authors: Kim
authors: Hee Jin
authors: HJ
authors: Chang
authors: Tae Hyun
authors: TH
authors: Kim
authors: Byung Chang
authors: BC
authors: Kim
authors: Dae Kyung
authors: DK
authors: Sohn
authors: Min Ju
authors: MJ
authors: Kim