Efficacy and Feasibility of Adding Induction Chemotherapy to Neoadjuvant Chemoradiation in Locally Advanced Rectal Cancer: A Phase II Clinical Trial.

Purpose: Currently, neoadjuvant chemoradiation (CRT) followed by total mesorectal resection is considered the standard of care for treating locally advanced rectal cancer. This study aimed to investigate the efficacy and feasibility of adding induction chemotherapy to neoadjuvant CRT in locally advanced rectal cancer.

Methods: This phase-II clinical trial included 54 patients with newly diagnosed, locally advanced (clinical T3-4 and/or N1-2, M0) rectal cancer. All patients were treated with 3 cycles of preoperative chemotherapy using the XELOX (capecitabine + oxaliplatin) regimen before and after a concurrent standard long course of CRT (45-50.4 Gy) followed by standard radical surgery. Pathologic complete response (PCR) rate and toxicity were the primary and secondary endpoints, respectively.

Results: The study participants included 37 males and 17 females, with a median age of 59 years (range, 20-80 years). Twenty-nine patients (54%) had clinical stage-II disease, and 25 patients (46%) had clinical stage-III disease. Larger tumor size (P = 0.006) and distal rectal location (P = 0.009) showed lower PCR compared to smaller tumor size and upper rectal location. Pathologic examinations showed significant tumor regression (6.1 ± 2.7 cm vs. 1.9 ± 1.8 cm, P < 0.001) with 10 PCRs (18.5%) compared to before the intervention. The surgical margin was free of cancer in 52 patients (96.3%). Treatment-related toxicities were easily tolerated, and all patients completed their planned treatment without interruption. Grade III and IV toxicities were infrequent.

Conclusion: The addition of induction chemotherapy to neoadjuvant CRT is an effective and well-tolerated treatment approach in patients with rectal cancer.