Application of short-course radiotherapy with total neoadjuvant therapy in the treatment of middle and low rectal cancer

Abstract

Objective: To compare the efficacy and safety of short-course radiotherapy with total neoadjuvant therapy (SCRT-TNT) and neoadjuvant chemoradiotherapy (nCRT) in patients with locally advanced middle and low rectal cancer. Methods: A retrospective cohort study was carried out. A of 126 patients with locally advanced middle and low rectal cancer who were treated in the Department of Gastrointestinal Cancer Surgery of Fujian Cancer Hospital from September 2016 to March 2020 were enrolled, including 73 males and 53 females, with a mean age of (56.5±9.8) (23-77) years. Based on neoadjuvant regimen (nCRT treatment was performed before December 2018 and SCRT-TNT treatment was carried out after January 2019), patients were divided into nCRT group (n=68) and SCRT-TNT group (n=58). There were no statistically significant differences in age, sex, distance from tumor to anal verge, Eastern Cooperative Oncology Group (ECOG) performance status and clinical TNM stage between the two groups (all P>0.05). Patients in both groups received pelvic intensity-modulated radiotherapy (IMRT). The radiotherapy dose of nCRT group was 50Gy/25 times/5 weeks. Patients in nCRT group received oral capecitabine chemotherapy during radiotherapy and underwent surgery 6-8 weeks after chemoradiation. However, patients in SCRT-TNT group received CapeOX regimen (oxaliplatin+capecitabine) for 2 cycles of induction chemotherapy, followed by short-course radiotherapy (25Gy/5 times/5 days), then underwent a radical surgery two weeks after completion of consolidation chemotherapy (4 cycles). The adverse reactions, perioperative safety and efficacy of neoadjuvant therapy were compared and analyzed between the two groups. Results: Both groups completed neoadjuvant therapy as planned. Patients in nCRT group and SCRT-TNT group had similar incidence of adverse reactions to radiotherapy and chemotherapy, however, there were no statistically significant differences in the incidence of surgical complications, operation time, intraoperative blood loss and postoperative length of hospital stay (all P>0.05). A total of 119 patients underwent total mesenterectomy (TME), including 64 patients in the nCRT group and 55 patients in the SCRT-TNT group, all with R0 resection. The pathological complete response (pCR) rate was 10.9% (7/64) in the nCRT group and 25.5% (14/55) in the SCRT-TNT group, respectively, with a statistically significant difference (P=0.038). Two years after surgery, there was no statistically significant difference in local recurrence rate and overall survival rate between the two groups (both P>0.05). However, the clinical metastasis rate of SCRT-TNT group was significantly lower than that of nCRT group (20.3% vs 9.1%), with a statistically significant difference (P<0. 05). Conclusion: SCRT-TNT do not increase the adverse reactions of radio chemotherapy and perioperative risks in the treatment of locally advanced middle and low rectal cancer, and the tumor regression effect is good, which is worthy of clinical promotion.