538P - The role of COX-2 and Ki-67 overexpression in the prediction of pathologic response of rectal cancer to neoadjuvant chemoradiation therapy

Date 01 October 2012
Event ESMO Congress 2012
Session Poster presentation III
Topics Rectal Cancer
Translational Research
Surgery and/or Radiotherapy of Cancer
Presenter Ali Taghizadeh Kermani
Authors A. Taghizadeh Kermani1, A. Jafarian2, J. Esmaeili2, N. Mohammadian Roshan2, M. Seilanian Toosi1, A. Omidi Ashrafi2, M. Karimi Shahri2
  • 1Oncology, MUMS, Mashhad/IR
  • 2Pathology, MUMS, Mashhad/IR

Abstract

Background

The response to neoadjuvant chemoradiotherapy (CRT) is not the same among all cases with advanced rectal cancer. Aims: In this study, we investigated the association between overexpression of two molecular markers (COX-2 and Ki-67) and tumor response to neoadjuvant therapy. Design: A retrospective cohort study.

Materials and methods

Forty five patients with stage II-III rectal carcinoma were enrolled. All patients were treated with neoadjuvant therapy (45-50.4 Gy plus Capecitabin) between 2002 and 2009 in our institute. The pretreatment specimens were IHC stained for COX-2 and Ki-67 markers. The tumor response to neoadjuvant treatment was evaluated using a 5 point tumor regression grade (TRG) system. The induced inflammation and necrosis after chemoradiotherapy were also investigated. Statistical analysis: Statistical analysis was performed using SPSS version 11.5 and statistical significance was determined at P < 0.05.

Results

The pathologic response to neoadjuvant treatment from complete response as (TRG = 1) through no response as (TRG = 5) was found in 10 (22.2%), 8 (17%), 6 (13.3%), 16 (35.6%), and 5 (11.1%) cases. In comparison with poor responders (TRG: 4,5), patients with good response to neoadjuvant treatment (TRG: 1,2) were associated with lower pretreatment mean COX-2 staining extent (72.9% vs. 22.8%, P < 0.001) as well as lower mean Ki-67 staining extent ( 70.7% vs. 28.5%, p < 0.001). High COX-2 staining and high Ki-67 index were significantly associated with more inflammation. Patients with high COX-2 expression showed also significantly more necrosis in their postsurgical specimens.

Conclusions

Overexpression of COX-2 and high Ki-67 index were associated with a poorer response to neoadjuvant chemoradiotherapy. These markers might be helpful to define those patients with rectal carcinoma who benefit more from neoadjuvant treatments.

Disclosure

All authors have declared no conflicts of interest.