582P - Predictors of response to preoperative chemoradiotherapy (CRT) for rectal adenocarcinoma: Biopsy specimens obtained 1 week after starting treatment...

Date 29 September 2014
Event ESMO 2014
Session Poster Display session
Topics Anti-Cancer Agents & Biologic Therapy
Rectal Cancer
Translational Research
Surgery and/or Radiotherapy of Cancer
Presenter Toshiyuki Suzuki
Citation Annals of Oncology (2014) 25 (suppl_4): iv167-iv209. 10.1093/annonc/mdu333
Authors T. Suzuki, S. Sadahiro, A. Tanaka, K. Okada, G. Saito
  • Gastrointestinal Surgery, Tokai University, 259-1193 - Isehara/JP

Abstract

Aim

Preoperative CRT is the standard of care for locally advanced rectal cancer. Patients who have pathological complete response (pCR) to CRT have good outcomes with a low risk of distant metastasis. We previously reported that changes in biopsy specimens obtained 1 week after the start of CRT are a reliable predictor of histologic response. We studied the relations between survival and changes in biopsy specimens, pCR, histologic marked regression and tumor shrinkage rate as evaluated by MRI.

Methods

The study group comprised 127 patients with clinical Stage II/III rectal adenocarcinoma who received CRT (40 to 45 Gy in 20-25 fractions with concurrent oral UFT or S-1) from 2006 through 2012. Surgery was performed 6 to 8 weeks after the completion of CRT. Biopsy specimens were obtained 1 week after the start of CRT and stained with hematoxylin and eosin (H-E). Patients showing moderate changes were assigned to group A, and those showing mild changes were assigned to group B. Patients with a pCR were classified as group C, and those with no pCR were classified as group D. Patients showing histologic marked regression were assigned to E group, and those without such regression were assigned to group F. Patients with a tumor shrinkage rate of 75% or higher were classified as group G, and those with a lower rate were classified as group H.

Results

The proportions of patients in each group were as follows: group A, 46%; group C, 17%; group E, 43%; and group G, 52%. The 5-year recurrence-free survival rate (RFS) and the 5-year overall survival rate (OS) were respectively as follows: 79% and 92% in group A vs. 59% and 79% in group B (p = 0.019, p = 0.127); 93% and 100% in group C vs. 64% and 82% in group D (p = 0.017 and p = 0.080); 78% and 95% in group E vs. 61% and 79% in group F (p = 0.008 and p = 0.022); and 71% and 88% in G group vs. 68% and 84% in group H (p = 0.423 and p = 0.480). Moderate changes on biopsy specimens and pCR were associated with higher rates of RFS, and histologic marked regression was associated with higher rates of RFS and OS.

Conclusions

Changes of H-E stained biopsy specimens 1 week after starting CRT were a prognostic factor. A pCR and marked histologic regression in resected specimens were also prognostic factors, but changes of biopsy specimens after 1 week of CRT had the important advantage of early availability.

Disclosure

All authors have declared no conflicts of interest.