Abstract
PURPOSE: Although chemoradiotherapy is considered an efficacious treatment option for patients with locally advanced rectal cancer, the associated radiological toxicities and late anal dysfunction are concerning issues. Herein, we examined the efficacy and safety of folinic acid, 5-fluorouracil, oxaliplatin, and irinotecan (FOLFOXIRI) as upfront therapy for marginally unresectable local rectal cancers without distant metastasis. METHODS: This multicenter, prospective, observational study was designed by the Yokohama Colorectal Cancer Study Group. The primary endpoint was the conversion rate. Secondary endpoints were the R0 resection rate, response rate, pathological response rate, postoperative complication rate, relapse-free survival, local progression-free rate, and circumferential resection margin-negative rate. RESULTS: Twenty patients were enrolled in this study. The study achieved its primary endpoint; the R0 resection rate was 80% (95% confidence interval, 56.3 to 94.3). Major grade ≥ 3 adverse effects included neutropenia in 7 (35%) patients, anemia in 3 (15%), fatigue in 2 (10%), enterocolitis in 2 (10%), febrile neutropenia in 1 (5%), leukopenia in 1 (5%), diarrhea in 1 (5%), fever in 1 (5%), and urinary tract infection in 1 (5%). CONCLUSION: FOLFOXIRI therapy was well tolerated and showed comparable efficacy results, providing potential R0 resection in patients with marginally unresectable locally advanced rectal cancer without distant metastasis. TRIAL REGISTRATION: UMIN Clinical Trials Registry (UMIN000040275).