Is long interval from neoadjuvant chemoradiotherapy to surgery optimal for rectal cancer in the era of intensity-modulated radiotherapy?: a prospective observational study

Hui Chang,1,2,* Wu Jiang,1,3,* Wei-Jun Ye,1,2 Ya-Lan Tao,1,2 Qiao-Xuan Wang,1,2 Wei-Wei Xiao,1,2 Yuan-Hong Gao1,2 1State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, People’s Republic of China; 2Department of Radiation Oncology, Sun Yat-sen University Cancer Center, Guangzhou, People’s Republic of China; 3Department of Colorectal Surgery, Sun Yat-sen University Cancer Center, Guangzhou, People’s Republic of China *These authors contributed equally to this work Objectives: To evaluate the impact of interval between neoadjuvant chemoradiotherapy (NACRT) and surgery on therapeutic and adverse effects of surgery, and long-term outcome of patients with locally advanced rectal cancer (RC), in the era of intensity-modulated radiotherapy (IMRT).Patients and methods: Patients diagnosed with stage II–III RC and treated with IMRT-based NACRT followed by radical surgery were enrolled consecutively from April 2011 to March 2014. The data of all the patients were collected prospectively and grouped according to their NACRT-to-surgery interval. The therapeutic and adverse effects of surgery, and survivals were compared between the patients with interval ≤7 weeks and those with interval ≥8 weeks.Results: A total of 231 patients were eligible for analysis, including 106 cases with interval ≤7 weeks and 125 cases with interval ≥8 weeks. The therapeutic and adverse effects of surgery were similar between these two groups of patients. However, interval ≥8 weeks appeared to lead to poorer overall, distant-metastasis-free and disease-free survivals, compared with interval ≤7 weeks. The HRs were 1.805, 1.714, and 1.796 (P-values were 0.045, 0.049, and 0.028), respectively.Conclusion: For patients with locally advanced RC, a long NACRT-to-surgery interval might bring a potential risk of increased distant metastasis rather than a better tumor regression in the era of IMRT. Keywords: rectal cancer, interval, neoadjuvant chemoradiotherapy, surgery, surviva