P-0297 Predictive/Prognostic Value of TS, KI-67, Egfr, MLH-1, MSH-2 and Trg in Locally Advanced Rectal Cancer Treated with Neoadjuvant Chemoradiation (Bmg-B1-Study)

Abstract

ABSTRACT Introduction Preoperative 5-fluorouracil/capecitabine based chemoradiation (CRT) is standard treatment in locally advanced rectal cancer (LARC) patients (pts). The aim of this Bologna Multidisciplinary Group (BMG-B1) study was to evaluate the predictive and prognostic value of Tumor Regression Grade (TRG) and pathological biomarkers (thymidylate synthetase/TS, epidermal growth factor receptor/EGFR, Ki-67, p53, Bcl-2, MLH1 and MSH2). Methods Between December 2001 to January 2011 we evaluated 149 pts with cT3-T4 N-/+ rectal adenocarcinoma and location ≤12 cm from the anal margin. Preoperative CRT consisted of radiotherapy 50.4 Gy in 28 daily fractions in combination with 5-fluorouracil continuous infusion or capecitabine +/- oxaliplatin. Rectal surgery with total mesorectal excision was performed 6-8 weeks after neoadjuvant treatment. Pathological examination of surgical specimens included the TRG according to Dworak (TRG0=no regression, TRG1=minor regression, TRG2=moderate regression, TRG3=good regression TRG4=complete regression). TS, EGFR, Ki-67, p53, Bcl-2, MLH1 and MSH2 were immunohistochemically determined in pretreatment biopsies and surgical specimens. Serial sections of formalin-fixed, paraffin-embedded tissues were stained with anti-TS (clone TS106/4H4B1, Zymed Lab. Inc., Invitrogen USA), anti-EGFR (clone DAK-H1-WT, DakoCytomation USA), anti-Ki-67 (clone MM1, Novocastra Lab.UK), anti-p53 (clone BP53-12, Novocastra Lab. UK), anti-Bcl-2 (clone 124, DakoCytomation. USA), anti-MLH1 (clone G168-15, Pharmingen, USA), anti-MSH2 (clone FE11, Zymed Lab. Inc., Invitrogen USA) using a biotin free ready-to-use amplification system (Dako Advance HRP, DakoCytomation DK). Results Immunohistochemistry results of 100 biopsies and 97 surgical specimens were available. After a median follow-up of 60.3 months (2-122) we observed 4.7% local recurrences, 12.7% distant recurrences, and 13.4% deaths. TRG grade 1, 2, 3, and 4 were observed respectively in 22.6%, 35.4%, 25.5%, 16.5% of patients. Patients with TRG grade 0-1 compared to patients with TRG grade 2-4 had significant worse disease free survival (DFS) (p=0.008) and overall survival (p=0.04). High TS expression in biopsy specimens is related with TRG grade 0-1 (p=0.009). High EGFR expression in surgical specimen is related with low DFS (p=0.01). The high decrease in Ki-67 expressions between biopsy and surgical specimen is related with TRG grade 3-4 (p=0.001). The others evaluated biomarkers did not showed clinical correlations. Conclusion In BMG-B1 Study TRG grade and EGFR expression in operative specimen after CRT showed a prognostic value. High TS expression in biopsy before CRT was related to worse pathological response, and high Ki-67 decrease after CRT is related to best response.