Relationship of FDG PET/CT Textural Features with the Tumor Microenvironment and Recurrence Risks in Patients with Advanced Gastric Cancers

SIMPLE SUMMARY: Radiomic analysis using textural features extracted from 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) images was performed to precisely predict metastasis and prognosis in patients with gastric cancer. However, the relationship between FDG PET/CT textural features and histopathological findings in gastric cancer has not been fully evaluated. This study investigated the textural features of gastric cancer on staging FDG PET/CT images with histopathological findings, including components of the immune microenvironment, and recurrence-free survival (RFS) after curative surgery. Textural features were associated with the histopathological classification, Lauren classification, the pN stage of gastric cancer, CD8 T lymphocytes, macrophage infiltrations, and matrix-metalloproteinase-11 expression in the tumor tissue. Textural features were significantly associated with RFS. Textural features of gastric cancer on FDG PET/CT could provide information regarding the histopathological features of cancer cells and the immune microenvironment, and they could be used to predict RFS. ABSTRACT: The relationship between 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) textural features and histopathological findings in gastric cancer has not been fully evaluated. We investigated the relationship between the textural features of primary tumors on FDG PET/CT with histopathological findings and recurrence-free survival (RFS) in patients with advanced gastric cancer (AGC). Fifty-six patients with AGC who underwent FDG PET/CT for staging work-ups were retrospectively enrolled. Conventional parameters and the first- and second-order textural features of AGC were extracted using PET textural analysis. Upon histopathological analysis, along with histopathological classification and staging, the degree of CD4, CD8, and CD163 cell infiltrations and expressions of interleukin-6 and matrix-metalloproteinase-11 (MMP-11) in the primary tumor were assessed. The histopathological classification, Lauren classification, lymph node metastasis, CD8 T lymphocyte and CD163 macrophage infiltrations, and MMP-11 expression were significantly associated with the textural features of AGC. The multivariate survival analysis showed that increased FDG uptake and intra-tumoral metabolic heterogeneity were significantly associated with an increased risk of recurrence after curative surgery. Textural features of AGC on FDG PET/CT showed significant correlations with the inflammatory response in the tumor microenvironment and histopathological features of AGC, and they showed significant prognostic values for predicting RFS.