Long-term outcomes and prognostic factors of preoperative chemoradiotherapy with oral dihydropyrimidine dehydrogenase inhibitory fluoropyrimidines in patients with locally advanced rectal cancer

BACKGROUND: The purpose of this study was to determine long-term outcomes and prognostic factors in patients with locally advanced rectal cancer who received preoperative chemoradiotherapy with oral dihydropyrimidine dehydrogenase (DPD)-inhibiting fluoropyrimidines. METHODS: Fifty-seven locally advanced rectal cancer patients who underwent preoperative chemoradiotherapy (CRT) with oral DPD-inhibitory fluoropyrimidines from 2006 to 2013 were retrospectively enrolled in this study. Patients with T3-T4 lower rectal cancer were irradiated once daily (2 Gy) with a total dose of 40 Gy, and chemotherapy was administered with tegafur-uracil (300 mg / m2 / day) or S-1 (80 mg / m2 / day) on radiation days. RESULTS: Five-year overall survival was 77.8% and 5-year disease-free survival was 65.1%. Recurrence was observed in 20 patients (35.1%) and local recurrence in 9 patients (15.8%). Multivariate analysis of prognostic factors for overall survival identified pre-CRT lateral lymph node metastasis and circumferential resection margin as independent prognostic factors, and ypStage as an independent prognostic factor for disease-free survival. CONCLUSIONS: Evaluation of lateral lymph node before CRT is useful in predicting prognosis in patients with locally advanced lower rectal cancer treated with preoperative chemoradiotherapy with oral DPD-inhibiting fluoropyrimidines, and surgical planning to ensure a 1-mm circumferential resection margin is important for improving prognosis. J. Med. Invest. 73 : 62-67, February, 2026.