Diagnostic and decision-making disparities in precision oncology in thoracic malignancies with interstitial...

Patients with thoracic malignancy and interstitial pneumonia (IP) are often excluded from clinical trials, consequently lacking quantitative evidence of poorer prognosis and lower programmed death-ligand 1 (PD-L1) testing rates.

We evaluated the real-world impact of comorbid IP on biomarker adoption and survival in thoracic malignancy patients receiving first-line systemic therapy at a tertiary teaching hospital between 2016 and 2023.

Among 1247 patients, 98 (7.5%) had comorbid IP. Multigene testing rates in IP patients were similar to those in non-IP patients. Only three actionable genomic alterations were found in the IP group, highlighting PD-L1 testing as the key element. PD-L1 testing was underutilized in the IP group (63.3%) compared with the non-IP group (75.1%). Immune checkpoint inhibitor (ICI) therapy was utilized in 12.2% of IP versus 29.3% in non-IP, despite comparable clinical situations. Comorbid IP predicted worse survival (hazard ratio: 1.789; 95% confidence interval: 1.373-2.331; p < 0.001). Although survival significantly improved in non-IP after 2020, no benefit was observed in IP. A multivariable model incorporating an IP × Period interaction confirmed comorbid IP remained a negative prognostic factor, highlighting recent advances have not bridged the survival disparity for this high-risk group.

Despite recent progress, patients with comorbid IP experience limited clinical benefit, characterized by lower rates of PD-L1 testing, restricted use of immune checkpoint inhibitors, and absence of post-2020 survival gains. This large-scale and quantitative evidence demonstrates persistent disparities and their prognostic significance, reflecting the limited applicability of current immunotherapy-based strategies in this high-risk population.