Role of bevacizumab in neoadjuvant chemotherapy and its influence on microvessel density in rectal cancer.

Abstract

The role of bevacizumab (Bev) in neoadjuvant chemotherapy (NAC) without radiotherapy for rectal cancer has not been fully discussed. The purpose of this study is to assess the clinicopathological benefit of Bev in NAC for rectal cancer and to investigate its influence on microvessel status in cancerous tissue. Data on 47 patients with rectal cancer, who received NAC with or without Bev between August 2008 and November 2012, were analyzed retrospectively. The objective response was evaluated using the maximum tumor diameter. Tumor regression grade 3/4 was classified as a pathological response. Thirty-one patients (66 %) received NAC that included Bev and the other 16 patients were treated without Bev. The objective response rate was significantly higher in the Bev group than in the non-Bev group (64.5 vs. 25.0 %, p = 0.015). The rate of pathological response was much higher in the Bev group (41.9 %) than in the non-Bev group (12.5 %), but did not reach significant difference (p = 0.052). Microvessel density (MVD) in the resected cancerous tissue was significantly lower in the Bev group than in the non-Bev group. We have confirmed that objective and pathological responses were better in patients treated with NAC that included Bev than in those who received NAC without Bev. Additionally, MVD in tumor tissues was inhibited in the patients treated with Bev. To investigate the impact of Bev in NAC on long-term survival, further follow-up is required.