Phase 2 multicenter randomized clinical trial: neoadjuvant chemoradiotherapy followed by D2 gastrectomy and adjuvant chemotherapy in patients with locally advanced gastric cancer

Introduction. Stomach cancer remains one of the most common malignancies with an unfavorable prognosis. It is the 5-th most frequent cancer and the 3rd leading cause of cancer death worldwide and in Russia as well. Combined modality treatment including radical surgery and perioperative / adjuvant therapy is the current therapeutic strategy for locally advanced gastric cancer. New approaches to combined modality treatment including neoadjuvant chemoradiotherapy for locally advanced gastric cancer were developed at A. Tsyb Medical Radiological Research Center (Obninsk, Russia) and tested in a phase 2 randomized clinical trial. The results obtained showed the safety and high efficiency of the method. To objectify the results, a multicenter randomized trial was initiated in 2016. The main objective of the study was to assess the immediate efficacy and safety of neoadjuvant chemoradiotherapy using pathological response criteria and to evaluate the frequency/severity of toxic reactions and postoperative complications. Additional objectives of the study were to assess the accuracy of preoperative staging of gastric cancer; tumor regression grade of the primary tumor and regional lymph node metastases according to CT findings; treatment outcomes according to the criteria of frequency and time to recurrence/metastasis; 1-, 2 -, and 3-year survival rates. Material and Methods. The study included 70 patients with equal distribution between the treatment groups. There were more males than women; the median age was 62 years. The main criterion for inclusion of patients into the study was morphologically confirmed gastric cancer of сT2-4N1-3, сT3-4N0-3; сМ0, IIA-IIIC stages. Patients of the first (investigated) group were treated with neoadjuvant chemoradiotherapy (total dose of 46 Gy in 23 fractions and chemotherapy with capecitabine and oxaliplatin) followed by surgery (gastrectomy/subtotal resection of the stomach with D2 lymph node dissection) and 4 cycles of adjuvant chemotherapy. Patients of the second (control) group underwent surgery (gastrectomy/subtotal resection of the stomach with D2 lymph node dissection) followed by 6 cycles of adjuvant chemotherapy. Results. The tumor was localized in the middle and lower thirds of the stomach in most cases. There were mostly low-grade adenocarcinomas (47 patients). None of the patients showed the presence of distant metastases; 2B and 3 clinical tumor stages were mostly observed. The comparison of clinical and pathomorphological stages in the control (surgical) group showed that a comprehensive examination, including CT and laparoscopy, allowed the correct assessment of the tumor stage and formation of the control group according to the main inclusion criteria in more than 90 % of patients. Comparison of patients between the study and control groups showed that they were well balanced on the main prognostically important factors. The differences between all parameters were not statistically significant (p>0.05).