Abstract 3316: Intra-tumor heterogeneity assessment of liver lesions for colorectal cancer patients on CT-scans

Abstract The objective is to find a consensus definition of intra-tumor heterogeneity of liver lesions for colorectal cancer patients on computed tomography (CT) scans and to evaluate the prognostic value of the newly defined criteria. 89 patients with colorectal cancer treated by antiangiogenics having standard pretreatment CT-scans were included. Lesions were manually segmented in a previous study. We reached a consensus definition by bringing three radiologists together to determine which criteria make a tumor heterogeneous. We asked two of the three radiologists to score lesions from one to three based on the consensus definition. A subset of 50 lesions was shared between annotators in order to check their agreement. 898 lesions were scored, which corresponds to a median of 6 lesions per patient. We associate a unique heterogeneity score to each patient defined as the difference between the number of very heterogeneous tumors and the number of heterogeneous tumors. The prognostic value of this heterogeneity score was assessed using a Cox regression. Intra-tumor heterogeneity of a single lesion is defined on a scale of one to three: homogeneous (pixels are of similar intensities), heterogeneous (pixels are of different intensities but organized as a ring), very heterogeneous (pixels are of different intensities and randomly organized). We note that the shape of the tumor is not taken into account in the heterogeneity assessment. The two radiologists agreed on the lesion heterogeneity score in 53% of cases. The patient heterogeneity score is significantly prognostic in both the univariate analysis (Kaplan-Meier estimator with median cut-off; p-value = 0.016) and the multivariate analysis (Cox model with control variables including gender, age, weight, treatment and tumor burden; p-value = 0.024). Three radiologists have reached a consensus to define intra-tumor heterogeneity of liver lesions for colorectal patients. According to this definition, intra-tumor heterogeneity was shown to be a prognostic factor. Citation Format: Ridouane Ghermi, Samy Ammari, Gabriel Garcia, Sana Harguem-zayani, Nathalie Lassau, Kathryn Schutte. Intra-tumor heterogeneity assessment of liver lesions for colorectal cancer patients on CT-scans [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3316.