Neoadjuvant radiotherapy in the complex treatment of locally advanced rectal cancer

Abstract

Introduction. Treatment of locally advanced rectal cancer (LARC) primarily aims to provide local control, increase the likelihood of sphincter preservation, and increase recurrence-free survival by affecting overall tumor volume and reducing the number of local metastatic lesions. A long course of preoperative radiation therapy (PT) combined with fluoropyrimidine-based chemotherapy followed by surgery at least 6 to 8 weeks later is the standard treatment for MRPC. However, the effectiveness and safety of treatment remain controversial in randomized controlled trials, which is relevant for the decision of the optimal approach to the complex treatment of patients with local spread of rectal cancer. Aim. The search for more effective regimens of preoperative chemoradiotherapy became the direction of clinical research. Materials and methods. The work is based on the analysis of the results of the treatment of 113 patients with locally advanced rectal cancer with T3c-4N1-2M0, with the presence of extramural vascular invasion (EMVI+), positive circular resection margin ≤ 1 mm (CRM+), who were treated in the radiotherapy and surgical departments of the communal enterprise Transcarpathian oncological center. In order to evaluate the clinical response of the tumor to neoadjuvant radioterapy (NRT), all 113 patients with LARC underwent a followup MRI examination of the pelvic organs after an average of 7.2 (95% CI 6.7 to 7.6) weeks. To evaluate the clinical effect, the scale for assessing the degree of tumor regression at MRI (TRG) was used. Results. Distant metastases after comprehensive treatment were diagnosed in 35 (30.9%) of 113 patients. All metastases occurred at a median follow-up of 15±3.6 months (from 5 to 42 months). In the main group, distant metastases were diagnosed in 15 (26.3%) patients, and in the control group – in 20 (35.7%) p>0.05. Late radiation damage was recorded in 9 (7.9%) patients: 4 (7%) in the main group and 5 (8.9%) in the control group. Most often, these were reactions from the organs of the gastrointestinal tract – in 5 (4.4%) patients. Reactions from the organs of the urinary system were observed in 3 (2.6%) cases, organs of the reproductive system – in 1 (0.8%) patient. The average time to the development of late radiation damage in the main group was 46.6±7.91 weeks after the end of the NRT course, and 49.5±6.34 weeks in the control group, p=0.033. In univariate variance analysis, prognostic factors such as PT technologies (VMAT and IMRT) and fractionation mode did not have a statistically significant effect on the frequency of development of late radiation injuries. Conclusions. The analysis of MRI data after the course of NRT and neoadjuvant chemoradiotherapy (NCRT) showed that the positive dynamics of replacement of tumor tissue by fibrosis was observed in 89 (78.7%) patients in the treatment groups. Complete clinical response was noted in 3.5% of patients in the main group and in 1.8% in the control group. In 86 patients of both groups, II and III degrees of tumor regression according to the TRG grading were recorded – in 43 (75.4%) patients of the main group and 43 (76.8%) patients of the control group.