575P - Biopsy specimens obtained 7 days after starting chemoradiotherapy (CRT) provides reliable predictors of response to CRT for rectal cancer

Date 01 October 2012
Event ESMO Congress 2012
Session Poster presentation III
Topics Rectal Cancer
Translational Research
Presenter Toshiyuki Suzuki
Authors T. Suzuki1, S. Sadahiro1, A. Tanaka1, K. Okada1, A. Kamijo1, S. Kawada2
  • 1Gastrointestinal Surgery, Tokai University School of Medicine, 259-1193 - Isehara/JP
  • 2Radiology, Tokai University School of Medicine, 259-1193 - Isehara/JP

Abstract

Background

Preoperative CRT is a standard treatment for locally advanced rectal cancer (LARC). The histologic response to CRT or the downstaging has been reported to be closely related to oncologic outcomes. Various biomarkers in biopsy specimens obtained before CRT have been investigated as predictors of response, however, reliable predictive biomarkers remain to be established.

Methods

The study group comprised 101 consecutive patients with LARC who received preoperative CRT of 45Gy with oral uracil/tegafur (UFT) or S-1. We evaluated histologic findings on H-E staining and immunohistochemical expressions of Ki67, p53, p21, and apoptosis in biopsy specimens obtained before CRT and 7 days after starting CRT. These findings were contrasted with the rate of histologic marked regression and the degree of tumor shrinkage.

Results

In biopsy specimens obtained before CRT, the degree of tumor shrinkage on barium enema (BE) were significantly greater in patients with p21-positive tumors (52 ± 11%) than in those with p21-negative tumors (45 ± 16%) (p < 0.01). In biopsy specimens obtained 7 days after starting CRT, the histologic marked regression according to the tumor regression grade (TRG) criteria was significantly higher in apoptosis-positive patients (57.1%) and p21-positive patients (49.2%) than in apoptosis-negative patients (30.1%) and p21-negative patients (20.0%) (p = 0.02 and p < 0.01, respectively). The degrees of tumor shrinkage based on BE and on MRI were both significantly higher in apoptosis-positive patients (55 ± 12%, 81 ± 15%) and p21-positive patients (52 ± 13%, 74 ± 19%) than in apoptosis-negative patients (45 ± 15%, 68 ± 19%) and p21-negative patients (41 ± 13%, 66 ± 19%) (p < 0.01, p < 0.01, p < 0.01 and p = 0.04, respectively). Histologic changes in H-E stained biopsy specimens significantly correlated with marked regression as well as with tumor shrinkage based on BE and MRI (p < 0.01, p < 0.01 and p = 0.03, respectively).

Conclusions

Immunohistochemical expressions of p21 and apoptosis together with histologic changes on H-E-stained biopsy specimens obtained 7 days after starting CRT are strong predictors of response to CRT.

Disclosure

All authors have declared no conflicts of interest.