Objective: to study the possibilities of Choi criteria in evaluating the objective response of metastatic colorectal cancer to transarterial chemoembolization (TACE), as well as to study the influence of the size and density of metastatic lesions on the posttreatment prognosis of the disease. Material and methods. CT data of 78 patients with colorectal cancer metastatic liver lesions before and after TACE with drug-eluted microspheres was analyzed. The posttreatment changes in the size and

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... ty of lesions were statistically analyzed. Evaluation of the treatment results was made according to Choi criteria and according to RECIST criteria. The effectiveness of both criteria was compared by analyzing progression-free survival (PFS) using the Kaplan-Meier method. The analysis of the influence of pretreatment size and density of lesions on the time to progression was done. Results. There was no significant reduction in the size of the liber lesions after TACE, but the density of the lesions decreased. According to the RECIST criteria, the stable disease was established in the majority of patients (73,1%). According to the Choi criteria, the majority of patients (65,4%) had a partial response. Response category coincided in 37,1% of observations. There were no significant differences in PFS between patients with different response categories according to RECIST criteria (p=0,052). PFS in patients with different response categories according to Choi criteria was different (p=0,000). There were no significant differences in PFS between patients with different sizes of foci before treatment (p=0,833). A higher density of foci before treatment provides higher PFS values (p=0,001). The sizes of lesions remain stable after TACE, but their density decreases. The Choi criteria are more effective in evaluating the TACE results of colorectal liver metastases than the RECIST criteria. The pretreatment lesions size is not a prognostic factor. Higher initial lesions density is associated with better treatment prognosis.