WCLC 2025 - Posters & ePosters-P2.08 .25 A Novel CT-Derived Biomarker of Immune Reserve Predicts Survival in Lung Cancer

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This study presents a novel, noninvasive biomarker derived from routine CT imaging—percent Thymic Tissue (pTT)—to estimate residual functional thymic tissue as a surrogate for immune reserve in adults with locally advanced non-small cell lung cancer (NSCLC). Thymic involution, the replacement of functional thymus by fat, progresses with age and is linked to immunosenescence, but no established method currently evaluates thymic function in adults noninvasively.<br /><br />Using a cohort of 399 stage III NSCLC patients, the authors employed a deep learning 3D convolutional neural network to segment the thymus on pre-treatment CT scans. A Gaussian Mixture Model classified thymic voxels into adipose or functional thymic tissue based on Hounsfield unit intensity, allowing quantification of pTT. Results showed that pTT declines with age and is lower in males, consistent with physiological thymic involution.<br /><br />Importantly, patients with high pTT (above 5.59%) had significantly better overall survival (log-rank p=0.015), and pTT remained an independent predictor after multivariable adjustment (adjusted hazard ratio 0.71, 95% CI 0.50–0.99, p=0.049). This suggests that pTT can serve as a meaningful biomarker of immune fitness influencing outcomes in NSCLC.<br /><br />The study concludes that pTT enables automated, noninvasive thymic assessment from standard imaging without manual input. It holds promise for integration into thoracic oncology prognostic models and may guide immunotherapy strategies. Future research directions include longitudinal evaluation of pTT changes post-treatment, correlation with immune parameters such as T-cell receptor profiles and thymic tissue specimens, and application in pediatric and other cancers. This work pioneers a quantitative imaging approach to measuring immune reserve with strong clinical relevance in lung cancer prognosis.

Asset Subtitle

Tafadzwa Chaunzwa

Meta Tag

Speaker Tafadzwa Chaunzwa

Topic Local-Regional Non-small Cell Lung Cancer

Keywords

percent Thymic Tissue

pTT

thymic involution

non-small cell lung cancer

NSCLC

immune reserve

CT imaging

deep learning segmentation

Gaussian Mixture Model

overall survival