Usefulness of monthly chemotherapy for patients with unresectable metastatic colorectal cancer.

Unresectable metastatic colorectal cancer with very slow tumour growth rate does not necessarily require for strong short-interval chemotherapy. In the present study, we administered monthly chemotherapy and aimed to evaluate the usefulness of the specific treatment schedule in patients with unresectable metastatic colorectal cancer with slow tumour growth rate. Since 2009, at our Institution, patients' whose serum carcinoembryogenic antigen (CEA) values on the treatment day were not higher than those before initial chemotherapy, and patients who did not wish to undergo intensive chemotherapy, were prospectively scheduled for specific chemotherapy. Between January 2009 and December 2011, 10 patients with unresectable metastatic colorectal cancer who received monthly chemotherapy were enrolled in the current study. During the same period, 14 patients with unresectable metastatic colorectal cancer were administered conventional-interval chemotherapy, oxaliplatin with oral S-1 (SOX) or capecitabine (XELOX), and comprised the control group. Three patients received first-line, four patients received second-line, and three patients received third-line treatment. All patients were able to receive a single-regimen of chemotherapy for more than a year. The survival of patients who received monthly chemotherapy was significantly better than survival of those who received SOX or XELOX within 30 months after starting chemotherapy (p<0.05). For patients with very slow tumour growth rates, our monthly chemotherapy may be beneficial.