Efficacy and safety of sequential neoadjuvant chemotherapy and short-course radiation therapy followed by delayed surgery in locally advanced rectal cancer: a single-arm phase II clinical trial with subgroup analysis between the older and young patients.

Purpose: This study was performed to investigate the efficacy and safety of short-course radiation therapy (SCRT) and sequential chemotherapy followed by delayed surgery in locally advancer rectal cancer with subgroup analysis between the older and young patients.

Materials and methods: In this single-arm phase II clinical trial, eligible patients with locally advanced rectal cancer (T3-4 and/or N1-2) were enrolled. All the patients received a median three sequential cycles of neoadjuvant CAPEOX (capecitabine + oxaliplatin) chemotherapy. A total dose of 25 Gy in five fractions during 1 week was prescribed to the gross tumor and regional lymph nodes. Surgery was performed about 8 weeks following radiotherapy. Pathologic complete response rate (pCR) and grade 3-4 toxicity were compared between older patients (≥65 years) and younger patients (<65 years).

Results: Ninety-six patients with locally advanced rectal cancer were enrolled. There were 32 older patients and 64 younger patients. Overall pCR was 20.8% for all the patients. Older patients achieved similar pCR rate (18.7% vs. 21.8; p = 0.795) compared to younger patients. There was no statistically significance in terms of the tumor and the node downstaging or treatment-related toxicity between older patients and younger ones; however, the rate of sphincter-saving surgery was significantly more frequent in younger patients (73% vs. 53%; p=0.047) compared to older ones. All treatment-related toxicities were manageable and tolerable among older patients.

Conclusion: Neoadjuvant SCRT and sequential chemotherapy followed by delayed surgery was safe and effective in older patients compared to young patients with locally advanced rectal cancer.