Brain metastases (BMs) are common in lung adenocarcinomas (ACs). Thyroid transcription factor 1 (TTF-1) is important in the diagnosis of AC. This study aimed to examine the relationship between TTF-1 and BM for the first time in literature. The data of 137 patients with AC that developed BM between 2009 and 2020 were retrospectively analyzed. A total of 137 patients, 120 (87.6%) male, and 17 (12.4%) female were examined. Their mean age was 59.78 ± 0.82 years. The Eastern Cooperative Oncology Group (ECOG) performance score was 0-1 (< 2) for 39 (28.5%) patients and 2-4 (≤ 2) for 98 (71.5%). TTF-1 was positive in 100 (73%) patients and negative in 37 (27%). More than five BMs were present in 102 (74.4%) patients and less than five in 35 (25.6%). All the patients received whole-brain radiotherapy. None of the patients was suitable for surgery or radiosurgery. The median survival time was 6.4 [95% confidence interval (CI), 5.67-7.1] months. The survival time was 7 (95% CI, 5.91-8.09) months for the TTF-1 (+) patients and 5.8 (95% CI, 4.1-7.5) months for the TTF-1 (-) patients. In the univariate analysis, there was a significant relationship between survival time and age (p = 0.047), TTF-1 (p = 0.024), and ECOG performance score (p = 0.002). The multivariance analysis revealed a significant relationship between survival and TTF-1 (p = 0.034) and ECOG score (p = 0.007). We found a correlation between survival time and ECOG performance score and TTF-1. TTF-1 can be used as a biomarker to monitor prognosis in the follow-up and treatment of patients with AC that develop BM.
© 2023. The Author(s).