There are three reasons to investigate protracted exposure to bevacizumab. Firstly, the agent, while inducing apoptosis, is considered a cytotoxic and protracted exposure is thought to be necessary to maintain tumor dormancy. Secondly, the studies in colorectal cancer treated patients until tumor progression. Lastly, there is an evolving paradigm in the treatment of ovarian cancer. It is now widely accepted that continual rather than intermittent palliative chemotherapy translates into a better quality of life. The Gynecologic Oncology Group have recently reported a provocative randomized controlled trial that confirmed a significant and large improvement in progression free survival (GOG 178), considered the most important end point in the patients with advanced ovarian cancer. Furthermore, in the preclinical studies of ovarian cancer, the ovarian cancer model presented a compelling argument for prolonged bevacizumab administration. Having inoculated the human ovarian carcinoma cell line SKOV-3 within the peritoneal cavity of immunodeficient mice, tumor engrafted in 7 to 10 days. The function-blocking VEGF antibody, A4.6.1 significantly inhibited subcutaneous SKOV-3 tumor growth approximately 20 fold compared with controls (P < 0.05), and similarly in the intraperitoneal model. Importantly, within 2 to 3 weeks of cessation of A4.6.1 treatment, effectively treated mice developed severe ascites, became cachectic, and had to be killed, and subsequent tumor burden in these animals varied from moderate to high. It should be clarified that the murine study utilized A4.6.1 the murine precursor of bevacizumab, but that the results can be extrapolated to the actions of bevacizumab.