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Introduction. A multimodal approach to the treatment of locally advanced gastric cancer with the addition of systemic or local treatment methods, such as chemotherapy and radiation therapy, reduces the risk of cancer recurrence, thus improving survival of patients. Advances in anticancer therapy dictate the need to develop systems for assessing tumor response to new treatment modalities.Material and Methods. The study included 162 patients with locally advanced gastric cancer who received treatment at the N.N. Petrov National Medical Research Center of Oncology from 2015 to 2018. All patients underwent subtotal gastric resection or gastrectomy with lymph node dissection and previously received neoadjuvant polychemotherapy. Patients were in the age range 30 to 80 years old. The tumor pathomorphological response to chemotherapy was assessed in all patients using a pathomorphological response rate system according to the classification of the Japanese Gastric Cancer Association (JGCA, 3rd English edition). All patients underwent computed tomography with pneumogastrography before neoadjuvant chemotherapy and immediately before surgery. For each of 162 patients, 96 qualitative and quantitative biomarkers of tumor and paragastric lymph node imaging were analyzed.Results. The accuracy of determining the tumor response rate using computed tomography with pneumogastrography was 82.6 % for TRG-0/1, 90 % for TRG-1/2, and 88 % for TRG-2/3. Discussion. The tumor pathomorphological response to treatment is a predictor of long-term results; however, it can be assessed only after analyzing the surgical specimen, and this marker cannot be used in inoperable cases and for correction of palliative chemotherapy. The study of imaging biomarkers based on quantitative and qualitative data reflecting the histopathological features of the tumor and lymph nodes can help determine the tumor regression grade and optimize treatment.Conclusion. The proposed algorithm for assessing the response grade of locally advanced gastric cancer to chemotherapy using imaging biomarkers is a promising prognostic marker and requires further study.

Objective: to reveal technical nuances for obtaining high-quality images using a computed tomography protocol with pneumogastrography and virtual gastroscopy, which contribute to the detection and assessment of the morphological type of gastric cancer and to the determination of its localization and invasion depth.Material and methods. The investigation enrolled 250 patients with both early (24.8%) and locally advanced (75.2%) gastric cancer treated in Petrov National Medical Research Center for Oncology from 2015 to 2018. Preoperative chemotherapy was performed in 142 (56.8%) patients and was not done in 108 (43.2%). All the patients underwent preoperative computed tomography with pneumogastrography and virtual gastroscopy. All the patients were radically operated on through subtotal or total gastric resection.Results. Computed tomography with pneumogastrography and virtual gastroscopy was used to detect gastric cancer in 98.4% of patients; the cases with early T1a and T1b invasion depth cancers were 23.2%. The tumor could not be significantly differentiated in 4 (1.6%) patients. This group consisted of: 3 (1.2%) and 1 (0.4%) patients with pT1a and pT1b invasion depth tumors, respectively. All non-visualized tumors had a superficial morphological type of growth (Type 0–II (3 cases with 0–IIa and 1 case with 0–IIb); their sizes were less than 2 cm. Three tumors were localized in the antral portion of the stomach; one was in its cardiac portion.Conclusion. Computed tomography with pneumogastrography and virtual gastroscopy is an effective technique to detect gastric cancer, including its early types of category T1, which makes it possible to assess its localization, morphological type, and invasion depth.