The impact of bevacizumab in metastatic colorectal cancer with an intact primary tumor: Results from a large prospective cohort study

Background Debate continues regarding the benefits versus risks of initial resection of the primary tumorin metastatic colorectal cancer (mCRC) patients with an asymptomatic primary tumor. Although the benefit of the anti-vascular endothelial growth factor agent bevacizumabalongside first-line chemotherapy in mCRC is established, the impact of bevacizumabon the intact primary tumor(IPT) is less well understood. Methods Data from an Australian mCRC registry were used to assess the impact of bevacizumab-based regimens in the presence of an IPT, to see if this differs from effects in resected primary tumor(RPT) patients and to understand the safety profile of bevacizumabin patients with IPT. Progression-free survival (PFS), overall survival (OS) and safety endpoints were analyzed. Results Of 1204 mCRC patients, 826 (69%) were eligible for inclusion. Bevacizumabuse was similar in both arms (IPT (64%) versus RPT (70%)); compared with chemotherapy alone, bevacizumabuse was associated with significantly longer PFS (IPT: 8.5 months vs 4.7 months, P = 0.017; RPT: 10.8 months vs 5.8 months, P < 0.001) and OS (IPT: 20 months vs 14.8 months, P = 0.005; RPT: 24.4 months vs 17.3 months, P = 0.004)).1 Bevacizumabuse in an IPT was associated with more GI perforations (4.5% vs 1.8%, P = 0.210) but less frequent bleeding (1.5% vs 5.3%, P = 0.050) and thrombosis (1.5% vs 2.7%, P = 0.470), versus chemotherapy alone. Median survival was equivalent between patients that did or did not experience bevacizumab-related adverse events – 20.0 months versus 19.9 months, hazard ratio = 0.98, P = 0.623.1 Conclusions The addition of bevacizumabsignificantly improved survival outcomes in mCRC with an IPT. The occurrence of bevacizumab-related adverse events did not significantly impact survivaloutcomes.