Tumor Necrosis on Routine Pretreatment CT as a Potential Prognostic Marker in Advanced NSCLC Treated With Immune Checkpoint Inhibitor Monotherapy: A Two-Center Retrospective Study.

Abstract

Background: The prognostic value of CT-detected tumor necrosis in advanced non-small cell lung cancer (NSCLC) treated with immune checkpoint inhibitor (ICI) monotherapy remains unclear. This two-center retrospective study investigated whether tumor necrosis on pretreatment CT independently predicts overall survival (OS).

Methods: A total of 151 advanced NSCLC patients who received ICI monotherapy between March 2016 and August 2021 at two Japanese institutions were retrospectively analyzed. Tumor necrosis was visually assessed and operationally defined as an intratumoral area of low attenuation or cavitary lesion ≥ 5 mm on pretreatment chest CT (contrast-enhanced in 113 patients [75%] and non-contrast in 38 [25%]). Cox regression analyses identified independent prognostic factors for OS, with internal validation using 1000 bootstrap resamples.

Results: Among 151 patients (mean age 69 years; 90% with ECOG PS 0-1), 121 (80%) had CT-detected necrosis. Median OS was significantly shorter in necrosis-positive patients than in necrosis-negative patients (374 vs. 1035 days; log-rank p = 0.02). A multivariate Cox regression analysis identified tumor necrosis as an independent adverse prognostic factor (HR = 1.84, 95% CI = 1.03-3.30; p = 0.04), along with blood-based biomarkers, tumor size, and PD-L1 expression. The detection rate of necrosis differed between CT modalities (contrast-enhanced 84% vs. non-contrast 68%, p = 0.04).

Conclusion: This exploratory two-center retrospective study indicates the potential of CT-detected tumor necrosis as a readily accessible prognostic marker in ICI-treated NSCLC. However, the results obtained require validation in larger, prospective, multicenter studies with standardized CT imaging protocols before clinical implementation.