Association between visceral adipose tissue radiodensity and overall survival among older adults with colorectal carcinoma.

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Background: Central obesity is a known risk factor for colorectal carcinoma (CRC); however, the association between visceral adipose tissue (VAT) and survival outcomes remains unclear. This study aims to investigate the relationship between VAT and overall survival (OS) among older adults with CRC. Methods: We analyzed data from the Cancer and Aging Resilience Evaluation registry, including adults aged ≥ 60 years with newly diagnosed CRC who were seen at the University of Alabama at Birmingham for initial consultation between October 2017 and April 2024. Using single-slice computed tomography staging scans, we calculated visceral adipose tissue radiodensity (VATD; in Hounsfield units, HU) at the third lumbar vertebra (L3) using validated methods. A lower VATD (more negative score) indicates higher visceral adipose tissue. Participants were followed until death or the study cutoff date of July 10, 2024. Kaplan-Meier survival analysis was performed to estimate OS for those with low VAT (VATD ≥ median VATD) versus high VAT (VATD < median VATD). Additionally, Cox proportional hazards models were utilized to evaluate the association between VATD and OS, adjusting for age at diagnosis, sex, race/ethnicity, skeletal muscle index (SMI), skeletal muscle density (SMD), and cancer stage. Results: A total of 190 patients were included, with a median age at diagnosis of 68 years (IQR: 64-75), 56% male, 72% non-Hispanic White, and 40% diagnosed with Stage IV disease. The median SMI and SMD were 42.06 (IQR: 33.81 - 49.52) cm ² /m ² and 38.68 HU (IQR: 31.38 - 44.89) respectively. The median VATD was -86.14 HU (IQR: -93.78 – -76.39). Over a median follow-up of 60 months, 96 patients (51%) died. Median OS was 27 months for patients with low VAT and 62 months for those with high VAT (log-rank test, p < .001). After adjusting for confounders, VATD remained independently associated with OS (adjusted Hazard Ratio: 1.41 per IQR decrease; 95% CI: 1.06 – 1.86; p ≤ .05), indicating that each IQR decrease in VATD scores (implying an increase in VAT) is associated with a 41% increased risk of all-cause mortality. Conclusions: Our findings demonstrate that increased visceral adipose tissue, indicated by more negative VATD scores, is significantly associated with poorer survival outcomes among older adults with CRC. These results underscore the importance of dietary and weight loss interventions to improve outcomes in this population.