Masahito Kotaka, Fusao Ikeda, Masaki Tsujie, Shinichi Yoshioka, Yoshihiko Nakamoto, Takaaki Ishii, Takahisa Kyogoku, Takeshi Kato, Akihito Tsuji, Michiya Kobayashi

There has been remarkable progress in systemic chemotherapy for metastatic colorectal cancer due to the widespread use of irinotecan, oxaliplatin, anti-vascular endothelial growth factor antibody, and anti-epidermal growth factor receptor antibody. It is important to continue treatment with the optimal combination of these drugs and prolong progression-free survival (PFS) to improve overall survival (OS). We conducted a prospective observational cohort study of 40 patients treated with XELOX plus bevacizumab for previously untreated metastatic colorectal cancer to investigate treatment continuity. Eligibility criteria were as follows: 1) histologically confirmed metastatic colorectal cancer; 2) lesions evaluable by imaging; 3) previously untreated; 4) suitable condition to receive XELOX plus bevacizumab; and 5) written informed consent. Outcomes were treatment continuity, overall response rate, resection rate, liver resection rate, time to treatment failure, PFS, and OS. Forty patients were enrolled and followed up for 2 years. Between July 2010 and June 2012, 40 patients were enrolled. The median number of treatment cycles was 7.5, and the reasons for discontinuation of treatment were as follows: complete response (five patients), resection (ten patients), progression (15 patients), adverse events (seven patients), and patient refusal (three patients). The overall response rate was 57.5%, resection rate was 25%, and liver resection rate was 15%. After a median follow-up of 31.4 months, the median time to treatment failure, PFS, and OS were 5.3, 13.3, and 38.9 months, respectively. Although the median time to treatment failure was 5.3 months, the median PFS and OS were prolonged to 13.3 and 38.9 months, respectively. This may have resulted from the chemotherapy-free interval due to complete response in five patients and resection in ten patients.