Analysis of PTEN, VEGF, HER2 and P53 Status in Determining Colorectal Cancer Benefit from Bevacizumab Therapy

Background: No factor has thus far been identified to predict the efficacy of bevacizumab therapy for colorectal cancer. We here therefore studied PTEN, VEGF, HER2 and p53 by immunohistochemistry as possible prognostic and predictive factors. Materials and Methods: A total of 34 retrospectively collected tumor samples were evaluated, all from patients receiving bevacizumab-based regimens. VEGF-A, PTEN, HER2, p53 were assessed and data was compared with clinicopathologic characteristics of patients and the bevacizumab response rate. Results: In this study, the median age of the 34 metastatic colorectal cancer patients was 55.5 (24-75), twelve (35.3%) being women and 22 (64.7%) men. PTEN, VEGF, HER2, p53 expressions were compared with bevacizumab response and other chacteristics of disease. Statistical significant differences were not found between bevacizumab response rates and different expression levels of VEGF, PTEN, HER2 and p53 (respectively p=0.256, p=0.832, p=0.189, p=0.131). However, a survival difference was noted in the VEGF expression negative group (median OS: 55 months; 95% CI, 22-88 months) (p=0.01). There was no statistically significant OS difference in other groups (PTEN p=0.6, HER2 p=0.189, p53 p=0.13). Conclusions: We did not find any predictive factor for BV therapy in our study. VEGF negative expression could be an important prognostic factor in metastatic colorectal carcinoma.