KEY POINTS
- This retrospective study used the TriNetX United States Collaborative Network across 70 healthcare organizations to compare prolonged versus shorter pembrolizumab exposure after chemoradiation for non-small cell lung cancer.
- Prolonged exposure required documented pembrolizumab use during months 9-14 after initiation. After propensity score matching, 450 patients were included in each cohort; the mortality analysis included 448 and 446 evaluable patients, respectively.
- All-cause mortality was 37.1% with prolonged exposure versus 46.4% with shorter exposure: risk difference -9.4% (95% confidence interval -15.8% to -2.9%; p=0.005) and risk ratio 0.798 (95% confidence interval 0.683-0.934).
- Median survival was 1,505 days versus 791 days, with a hazard ratio of 0.674 (95% confidence interval 0.550-0.827; log-rank p<0.001).
- Hospital admission, critical care utilization, palliative care encounters, and emergency care did not differ significantly. However, treatment duration was not modeled as a time-dependent exposure, creating substantial immortal time and survivor bias.
CLINICAL TAKEAWAY
Prolonged pembrolizumab exposure may identify patients with favorable outcomes after chemoradiation, but this study cannot establish that longer treatment independently improves survival. Missing stage, performance status, programmed death-ligand 1 expression, response, toxicity, and discontinuation data further limit causal interpretation, making the findings hypothesis-generating rather than practice-changing.
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