Abstract 3721: Critical role of Bevacizumab schedule in combination with chemo-radiotherapy in neo-adjuvant treatment of rectal cancer: Circulating endothelial cells and FDG-PET as markers for early prediction

Vascular endothelial growth factor (VEGF) has a crucial role in tumor angiogenesis, and its inhibition by bevacizumab (BEV) leads to normalization of tumor vessels increasing tumor oxygenation and drug delivery. However, the clinical benefits of current anti-VEGF treatments have thus far been rather modest, stimulating interest in developing novel effective ways to combine anti-VEGF drugs and chemotherapy (CT) and in the identification of valid predictive biomarkers of clinical benefit. We have previously shown that pre-operative oxaliplatin (OXA), raltitrexed (RTX), fluorouracil (5FU), and folinic acid (LFA) during pelvic radiotherapy (RT) have high rate of complete (TRG1) or subtotal (TRG2) tumor regression in locally advanced rectal cancer. In this study in order to demonstrate the relevance of the timing of BEV added to primary CT and RT we evaluate two different schedules of treatment. Changes of CECs and …