513P - Impact of Tumour Site on Bevacizumab Efficacy in Metastatic Colorectal Cancer (Mcrc)

Abstract

ABSTRACT Aim: With an ever-increasing focus on personalised medicine, all factors known to affect treatment response need to be considered when defining optimal therapy for individual patients (pts). While the prognostic impact of primary tumour site on CRC outcomes is established, emerging data suggest potential differences in response to biologic therapies. Here we explore the impact of tumour site on bevacizumab (BEV) efficacy in pts with mCRC. Methods: Analysis of pts in an Australian prospective multicentre mCRC registry who received first-line palliative chemotherapy from July 2009 to March 2014. Tumour site was defined as: right colon (RCC)–caecum to transverse, left colon (LCC)–splenic flexure to rectosigmoid, and rectum (RC). Kaplan-Meier and Cox models were used for survival analyses. Results: Of 698 pts, 224 had RCC, 266 LCC and 208 RC primaries. Median age was 69, 66 and 63 years respectively (p Median PFS (months) Bevacizumab vs no bevacizumab Hazard ratio * 95% CI P value RCC 8.7 vs 5.6 0.60 0.42-0.85 0.004 LCC 11.8 vs 8.3 0.69 0.49-0.96 0.028 RC 13.5 vs 9.1 0.74 0.51-1.06 0.101 * Adjusted for age, sex, PS, comorbidity. Conclusions: Tumour site was prognostic in this cohort, with RC and RCC associated with best and worst outcomes respectively. Patients who received bevacizumab in addition to chemotherapy had superior PFS, with the effect appearing greatest in RCC patients. Although known prognostic factors were adjusted for, other clinicopathologic differences that may contribute to patient outcomes cannot be excluded. Patient accrual is ongoing and molecular analyses are planned. Disclosure: H. Wong, A.J. Lomax, M. Tacey, J. Shapiro, A. Zimet, D. Yip, R. Jennens, G. Richardson, J. Tie, S. Kosmider P. Parente, L. Lim, P. Cooray, B. Tran, J. Desai and B. Wong: Roche Products Pty Ltd (Australia) has provided financial assistance for the development, installation and maintenance of this clinical database. K. Field and L. Nott declare: Roche Products Pty Ltd (Australia) has provided financial assistance for the development, installation and maintenance of this clinical database. I have also received honoraria and other renumeration from Roche. J. McKendrick: Roche Products Pty Ltd (Australia) has provided financial assistance for the development, installation and maintenance of this clinical database. I also have an advisory relationship with Roche. P. Gibbs: Roche Products Pty Ltd (Australia) has provided financial assistance for the development, installation and maintenance of this clinical database. I have also received honoraria from Roche.