Effect of short-course radiotherapy followed by oxaliplatin-based consolidation chemotherapy on organ preservation in locally advanced rectal cancer.

PURPOSE: We analyzed the effectiveness, safety, and mid-term oncological outcomes of short-course radiotherapy (SCRT) and oxaliplatin-based consolidation chemotherapy in patients with locally advanced rectal cancer (LARC). METHODS: We retrospectively evaluated 64 patients with LARC who underwent SCRT and tegafox (tegafur-uracil/leucovorin plus oxaliplatin) or mFOLFOX-6 (5-fluorouracil, leucovorin, and oxaliplatin) consolidation chemotherapy before surgery between January 2015 and December 2020. Tumor response, patient compliance, toxicity, surgical outcomes, overall survival (OS), and disease-free survival (DFS) were analyzed. RESULTS: Sixty-four patients with a mean age of 58.67 years (44 males) were included; 48 (75%) had tumors within 5 cm of the anal verge. Additionally, 93.8% of the patients underwent at least 2 months of chemotherapy, and three required dose reduction. Grade III toxicity occurred in 2 patients, and 10 had a clinical complete response and opted for non-operative management. One patient experienced tumor progression and underwent further treatment without surgery. Among the 53 patients who underwent surgery, 51 (96.2%) had sphincter preservation, 3 had Clavien-Dindo grade III complications, and no mortality occurred. The complete response rate for the entire cohort was 23.4%. Moreover, 47 patients (74.6%) had a neoadjuvant rectal score of < 16 after treatment. After a median follow-up time of 32.01 months, 6 (9.3%) had local recurrence, and 17 (26.6%) had distant metastasis. The 3-year OS, DFS and stoma-free rates were 89.5%, 65.5%, and 78.1% respectively. CONCLUSION: SCRT followed by oxaliplatin-based consolidation chemotherapy is safe and effective for tumor downstaging in LARC, further improving the sphincter preservation rate.