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.

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. 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). 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. 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.