Predictive significance of VEGF and HIF-1α expression in metastatic colorectal cancer patients receiving chemotherapy combined with bevacizumab.

Abstract

e14672 Background: There is no suggested molecular indicator in identifying which patients will benefit from anti-angiogenic treatment in metastatic colorectal cancer. Over expression of vascular endothelial growth factor (VEGF) and Hypoxia Inducible Factor 1-alpha (HIF-1α) are associated with bad prognosis. In this study, VEGF and HIF-1α expression and their clinical significance are studied in tumor tissues of patients with colorectal cancer receiving treatment with bevacizumab. Methods: VEGF and HIF-1α were observed immunohistochemically in primary tumors of 53 patients. The expressions were separated by evaluating low and high of VEGF and HIF-1α expression. We evaluated whether expression of VEGF and HIF-1α can help to predict treatment response, progression free survival (PFS), and overall survival (OS). Results: Fifty-three patients were enrolled in the study. Median age was 55. VEGF was strongly expressed in 30 patients (57%) whilst low expression was observed in 23 of them (43%). When VEGF expression was evaluated in association with therapy response rates; the clinical benefit rate was 38% in the low expression group whereas it was 62% in high expression group. This difference was statistically significant (p=0.01). In the group with strong VEGF expression PFS was 10 months whereas it was 8 months in the low expression group (p=0.009). When evaluated for OS, 26 months versus 15 months was in favor of highly expressed VEGF group (p=0.03). Highly expressed HIF-1α was found in 29 patients (55%), on the other hand low expressed HIF-1α was detected in 24 (%45) patients. For clinical benefit rates, PFS and OS there was no difference between high and low expressed HIF-1α groups. Conclusions: It has been demonstrated that VEGF and HIF-1α expressions are associated with poor prognosis in several tumors, mainly colorectal carcinomas. With the better understanding of carciogenesis and angiogenesis at molecular level, especially VEGF and HIF-1α became target molecules of the therapy. According to results of our study, VEGF expression is a predictive factor in designating the metastatic colorectal cancer treatment.