Efficacy and safety of different neoadjuvant radiation doses in patients with local advanced rectal cancer：A retrospective study

Abstract Background: The research aimed to evaluate the efficacy and safety of different radiation doses (45Gy and 50.4Gy) on neoadjuvant in patients with LARC.Methods: Patients with LARC between January 2016 and June 2021 were retrospectively enrolled in the study, all of them underwent neoadjuvant chemoradiotherapy and radical surgical. XELOX regimen was administered for two cycles before nCRT. 72 patients received radiation dose with 50.4Gy while 45 patients with 45Gy. During radiotherapy, concurrent chemotherapy was employed as capecitabine alone. Surgery was performed within 5-12 weeks after nCRT.Results: Baseline characteristics in both groups were not statistically significant. The rate of well pathological regression in the 50.4Gy group was 59.72% (43/72) while in the 45Gy group was 64.58% (31/48) (P>0.05). The rate of radiographic remission in the 50.4Gy group was 70.83% (51/72), compared with 68.75% (33/48) in the 45Gy group(P>0.05). Significant differences existed in the incidence of several adverse events (radioactive proctitis, myelosuppression and intestinal obstruction or perforation) between the 50.4Gy group and the 45Gy group(P<0.05).Conclusions: Higher radiation dose could increase the incidence of several adverse events, meanwhile, it failed to improve the rate of pathological regression and imaging remission.