results of neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer. Comparative efficiency of hypofractionation and classical fractionation schedules

Objective: comparison of the effectiveness of the results of neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer using classical and hypofractionated schedule of radiation therapy.Materials and methods. This study is based on a retrospective analysis of a database of patients with locally advanced rectal cancer (T3C–D, positive circumferential resection margin or T4) who underwent a prolonged course of neoadjuvant chemoradiotherapy followed by surgery. The patients were divided into two groups: the first (main) group, 71 patients who received a course of chemoradiotherapy in hypofractionation schedule as part of neoadjuvant treatment (4 Gy × 40 Gy, 3 fractions per week) in combination with chemotherapy with capecitabine 1650 mg / m2 in two doses on weekdays. The second group (control group) included 79 patients who treated with long-course chemoradiotherapy in the classic fractionation mode (2 Gy × 50–58 Gy, 5 fractions per week) in combination with chemotherapy with capecitabine 1650 mg / m2 in two doses on weekdays. In the preoperative period, along with chemoradiotherapy, 4–8 courses of the systemic chemotherapy in the CapOx mode was used. The primary endpoint of this study was pathological complete response. Secondary endpoints included the seve rity of early radiation and hematological toxicity, the incidence of local recurrence, distant metastases, overall and disease-free survival. Results. The study included 150 patients. The overall frequency of acute radiation toxicity of grade III–IV was 5.6 % in the main group and 8.9 % in the control group (p = 0.658), from them hematological toxicity – 2.82 % and 7.6 %, respectively (p = 0.350), skin and pelvic organ toxicity – 2.82 % and 1.3 %, respectively (p = 0.926). Complete pathological response of III degree in the groups achieved 22.5 % and 19 %, respectively (p = 0.593), grade IV – 18.3 % and 15.2 %, respectively (p = 0.829). In the main and control groups, 4.2 % and 3.8 % of local recurrence were registered, respectively (p = 0.954; hazard ratio (HR) 1.05; 95 % confidence interval (CI) 0.21–5.22). The median time of disease-free survival was 39.4 months. The three-year disease-free survival in the main group was 73.2 % and in the control group 64.6 %, respectively (p = 0.353; HR 0.79; 95 % CI 0.42–1.35). The three-year overall survival in the main and control groups were 84.5 % and 82.3 %, respectively (p = 0.743; HR 0.87; 95 % CI 0.39–1.92). Conclusions. The hypofractionation schedule can be considered as an alternative and not inferior to the standard dose fractionation regimen in a prolonged course of neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer.