Orbital fat as an imaging biomarker of nutritional status and systemic inflammation in patients with non-small cell lung cancer

Orbital fat has recently attracted attention as a unique adipose tissue compartment with potential metabolic and inflammatory significance. However, its relationship with nutritional status and systemic inflammation in patients with non-small cell lung cancer (NSCLC) remains poorly understood. This study aimed to evaluate orbital fat volume and radiological density on computed tomo g raphy (CT) and to investigate their associations with body mass index (BMI) and systemic inflammatory markers in patients with NSCLC. A retrospective study included 86 patients with histologically confirmed NSCLC. Orbital fat was semiautomatically se g mented on CT images using the 3D Slicer software. Total orbital fat volume and mean radiological density expressed in Hounsfield units (HU) were calculated for each patient. Clinical data and complete blood - count-derived inflammatory markers, including neutr o phil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII), were collected from medical records. Associations between orbital fat parameters and clinicopathological characteristics were assessed using Pea r son’s chi-square test, Spearman’s correlation analysis, and multivariable linear regression models. The mean orbital fat volume was 9.7 ± 1.4 cm³, while the mean radiological density was 77.0 ± 6.9 HU. Patients with larger orbital fat volume demonstrated signif i cantly higher BMI and lower levels of NLR, PLR, and SII. Orbital fat volume showed a positive correlation with BMI (ρ = 0.561, P < 0.001) and negative correlations with NLR (ρ = −0.242, P = 0.025), PLR (ρ = −0.361, P < 0.001), and SII (ρ = −0.335, P = 0.002). Radiological density was positively associated with BMI (ρ = 0.689, P < 0.001) and inversely correlated with PLR (ρ = −0.412, P < 0.001) and SII (ρ = −0.220, P = 0.042). In multivariable analyses adjusted for BMI, the associations between orbital fat volume and inflammatory markers lost statistical significance. By contrast, radiological density remained independently associated with PLR (β = −0.013, P = 0.007). These findings suggest that orbital fat volume primarily reflects nutritional status in patients with NSCLC, wher e as radiological density may provide additional information regarding systemic inflammation. Quantitative CT assessment of orbital fat represents a promising noninvasive imaging biomarker of metabolic and inflammatory alterations in this patient population.