Fat Attenuation Index of Renal Cell Carcinoma Reveals Biological Characteristics and Survival Outcome

Abstract

PurposeThe computed tomography fat attenuation index (FAI) is an ideal quantifiable imaging factor to identify the inflammation degree of peri-tumor adipose tissue. We aimed to verify whether FAI could reflect peri-tumor adipose inflammation, predict the survival outcome of renal cell carcinoma (RCC), and discover transcriptomic features of tumor tissues and adjacent adipocytes.Materials and MethodsTwo clinical cohorts (Fudan University Shanghai Cancer Center [FUSCC] cohort [n=129] and TCGA cohort [n=218]) were used to explore the association between FAI and clinical outcome. A prospective cohort (n = 19) was used to discover the molecular phenotyping of peri-tumor adipose tissue and tumor tissue according to their FAI value. A clinical cohort (n = 32) in which patients received cyto-reductive surgery was used to reveal the dynamic change of FAI.ResultsA high peri-tumor FAI was significantly associated with a worse outcome in both the FUSCC (HR = 2.28, p = 0.01) and the TCGA cohort (HR = 2.24, p <0.001). The analysis of the RNA expression of paired RCC tissue and peri-tumor fat tissue showed synchronized alterations in pathways such as cytokine–cytokine receptor interaction and complement and coagulation cascades. RCC tissues showed significant alterations in the neuroactive ligand–receptor interaction pathway. Immune deconvolution analysis showed enhanced infiltration of macrophages in high FAI tumor tissues with a lower angiogenesis level. We also observed synchronous dynamic changes in FAI and tumor size after targeted therapy.ConclusionIn summary, FAI could be used in RCC to reflect the biological characteristics and tumor immune micro-environment of both the tumor and the peri-tumor adipose. High peri-tumor FAI had the potential to predict a worse survival outcome in various cohorts. This study demonstrates that the crosstalk exists between a tumor and its micro-environment and could be reflected easily by imaging procedures, which could facilitate clinical decision making.

Prognostic Impact of Visceral Adipose Tissue Imaging Parameters in Patients with Cholangiocarcinoma after Surgical Resection

“…The prognostic significance of CT attenuation and FDG uptake of adipose tissue has yet to be evaluated in patients with cholangiocarcinoma. However, VAT HU and VAT SUV have been shown to be significant prognostic factors for predicting survival in other cancers in the abdominopelvic cavity, including colorectal cancer, gastric cancer, hepatocellular carcinoma, pancreatic cancer, and renal cell carcinoma, all of which grow in adipose tissue-dominant environments [11,12,14,15,23,24]. In the present study, among the adipose tissue imaging parameters, VSR, VAT HU, and VAT SUV were found to be significant predictors for RFS on univariate survival analysis, and VSR and VAT SUV remained as independent predictors for RFS on multivariate analysis after adjusting for age, sex, obesity, TNM stage, and extent of resection.…”