Possibilities of combined PET/CT with 18F-FDG in evaluating the effectiveness of targeted therapy in patients with non-small cell lung cancer

Introduction. Early assessment of the effect of targeted therapy in patients with non-small cell lung cancer (NSCLC) and a mutation in the EGFR gene is important for the timely correction of antitumor therapy.Aim: To study the possibilities of combined positron emission and computed tomography with 18F-fluorodeoxyglucose (PET/ CT with 18F-FDG) using the RECIST 1.1 and PERCIST 1.0 criteria. In a comparative assessment of the effect of various targeted therapy options in patients with NSCLC and a mutation in the EGFR gene.Material and Methods. The study included 86 patients with stage II-IV NSCLC, including 56 patients with a mutation in the EGFR gene. Of these, 32 patients received targeted monotherapy with tyrosine kinase inhibitors (TKI) - gefitinib or erlotinib and 24 patients received combination therapy (TKI + bevacizumab). The control group consisted of 30 patients who received platinum-containing chemotherapy drugs in combination with bevacizumab. The effect of antitumor therapy was evaluated using the combined PET method/CT with 18F-FDG using RECIST 1.1 and PERCIST 1.0 criteria. The results of the study were compared before the start of treatment and after 4-6 weeks of treatment.Results. In the repeated study of PET/CT with 18F-FDG, a partial positive response to the treatment of both tumor foci and affected regional lymph nodes according to the metabolic criteria PERCIST 1.0. was observed 1.3-1.8 times more often than when using the anatomical criteria RECIST 1.1. (p = 0,049). The frequency of а positive response to treatment in patients receiving targeted monotherapy was quite comparable to that in patients in the control group (43.7 and 40.0%, respectively). Based on 18F-FDG repeat PET/CT and PERCIST 1.0 metabolic criteria in patients receiving combined targeted therapy, a partial positive effect of treatment (58.3%) was observed 1.4 times more often, and disease progression was 4 times less common than in the subgroup of targeted monotherapy and in the control group (p = 0,043).Conclusions. Possibilities of early assessment of the effect of antitumor therapy using PET/CT with 18F-FDG increase when using the metabolic criteria PERCIST 1.0 - more sensitive than the anatomical criteria RECIST 1.1. According to PET/CT with 18F-FDG in patients with NSCLC and a mutation in the EGFR gene, the effect of combined therapy of TKI in combination with bevacizumab significantly exceeds not only the result of targeted monotherapy, but also the effect of chemotherapeutic treatment of patients in the control group.