A Prospective, Single-arm, Multicenter Trial of Diverting Stoma Followed by Neoadjuvant Chemotherapy Using mFOLFOX6 for Obstructive Colon Cancer: YCOG 1305 (PROBE Study).

Abstract

We conducted the first prospective clinical trial of neoadjuvant chemotherapy for patients with obstructive colon cancer. Obstructive colorectal cancer is locally advanced colorectal cancer with a poor prognosis. The effect of neoadjuvant chemotherapy for obstructive colon cancer is unclear. We conducted a single arm, multicenter trial involving patients from the Yokohama Clinical Oncology Group with obstructive colon cancer. All eligible patients underwent diverting stoma formation before neoadjuvant chemotherapy. Patient received 6 cycles of mFOLFOX6 followed by primary tumor surgery and then 6 cycles of adjuvant chemotherapy. The primary endpoint was the objective response rate of all intended neoadjuvant therapy. The study was registered with the Japanese Clinical Trials Registry as UMIN000013198. Between April 2014, and July 2016, 50 patients were registered, and 46 received neoadjuvant chemotherapy. The objective response rate as the primary endpoint was 67.4%. The most common grade >3 adverse event associated with neoadjuvant chemotherapy was neutropenia (28.3%). Forty-five patients underwent surgical resection of the primary lesion (R0 resection in all cases). Grade >2 surgery-related complications occurred in 7 patients (15.6%). The downstaging rate was 48.9%, and the moderate or greater regression rate was 52.2%; no cases showed pathological complete response. Adjuvant chemotherapy with mFOLFOX6 was performed in 34 patients (75.6%). The 3-year relapse-free and overall survival rates were 76.5% and 95.4%, respectively. Neoadjuvant chemotherapy using mFOLFOX6 was feasible and might be a treatment option for patients with obstructive colon cancer. Further large-scale studies are warranted to confirm the present findings.