TTF-1 negativity in synchronous M1b/M1c wildtype lung adenocarcinoma brain metastases predicts worse survival with increased risk of intracranial progression.

Background: Thyroid Transcription Factor-1 (TTF-1) expression in lung adenocarcinoma (LUAD) has been studied for its prognostic value in early-stage and metastatic disease. Its role in brain metastasis remains unexplored. This study investigates the predictive value and association of TTF-1 status with clinicopathological variables in patients with synchronous LUAD brain metastases.

Material And Methods: In this bicentric retrospective study, 245 patients with newly diagnosed, treatment-naïve brain metastasis undergoing resection were included. Patient data were retrieved from electronic records. Outcomes included overall and progression-free survival. Statistical analysis included Kaplan-Meier estimates and Cox proportional hazards regression.

Results: Mean Ki67 index in TTF-1 negative patients was 43% [95% CI 38-48%] compared to 32% [95% CI 29-35%] in TTF-1 positive (TTF-1 +) patients (p < 0.001). Tumor volume was significantly larger in TTF-1 negative (TTF-1-) patients (mean volume 24 mL [95% CI 18-31 mL]) vs. 15 mL [95% CI 12-17 mL] in TTF-1 + patients (padjust = 0.003). Perifocal edema was smaller in TTF-1- patients (mean volume: 58 mL [95% CI 45-70 mL]) vs. 84 mL [95% CI 73-94 mL] in TTF-1 + patients (padjust = 0.077). Tumor and edema volume did not correlate. TTF-1- patients showed worse overall, intracranial, and extracranial progression-free survival. In a multivariable Cox model, positive TTF-1 status was independently associated with improved outcomes. Negative TTF-1 status was associated with increased hazard for intracranial disease progression compared to extracranial progression.

Conclusion: In synchronous LUAD brain metastases, TTF-1 negativity reflects an aggressive phenotype with larger proliferation capacity and tumor volume. Future research should explore the underlying cellular and molecular alterations of this phenotype.