Chemoradiotherapy in the Combined Treatment of Patients with Rectal Cancer: Experience of A. Tsyb MRRC; Химиолучевая терапия в комбинированном лечении больных раком прямой кишки — опыт МРНЦ им. А.Ф. Цыба

Introduction. The standard treatment for patients with lower and middle ampullary rectal cancer (RC) is a combination of radiation and chemotherapy with total mesorectal excision (TME). However, only about 15 % of patients who undergo standard chemoradiotherapy at a dose of 50 Gy and fluoropyrimidine drugs achieve a pathological complete response (pCR) to treatment. The use of consolidation chemotherapy (CCT) between CRT and surgery is aimed at improving patient survival and increasing the number of complete responses. Aim. To analyze the immediate and long-term results of the use of chemoradiotherapy with 4 cycles of CCT in the treatment of patients with locally advanced RC. Materials and methods. Since 2018, A. Tsyb MRRC has been using CRT with 4 cycles of CCT for the treatment of locally advanced RC. In this trial, all patients were to receive radiation therapy a total dose of 50 Gy in combination with capecitabine administered orally at a daily dose of 825 mg/m2. Conventional irradiation was delivered using a linear accelerator with the four-field isocentric irradiation technique. Patients enrolled in the trial since June 2021 have received conformal radiation using rotational therapy with volumetric intensity-modulated arc radiotherapy (VMAT - RapidArc) and volumetric image-guided IGRT (CBCT). Results. The study included 192 patients with lower and middle ampullary RC. Most patients had stage III disease - 79.2 % (n = 152). A total of 190 patients (98.9 %) received a full course of radiation therapy. At follow-up, 20 patients (10.4 %) had a clinical complete response (cCR). Thirteen of these (65.0 %) were in the active surveillance program group. Seven patients with cCR underwent surgery. TME was performed in 147 (76.6 %) patients, including 31 (21.1 %) patients with pCR. Overall, the complete response rate, including patients in the active surveillance arm (cCR+pCR), was 27.1 % (52 cases). The overall three-year survival rate for the entire group of patients was 82.5 ± 3.2 %. Conclusion. CRT with 4 cycles of CCT is a safe regimen, resulting in a complete response in 27.1 % of patients. The use of the active surveillance program is indicated for patients with cCR. In patients with a good response to CRT (mrTRG1-2), there is a need to further improve instrumental diagnostic methods to identify cCR. © 2025 Elsevier B.V., All rights reserved.