BACKGROUND: This study investigates the correlation between blood-brain barrier (BBB) damage and cognitive impairment in patients suffering from untreated lung cancer. The study aims to understand the impact of BBB permeability on cognitive function and brain structure in this patient population. PATIENTS AND METHODS: This study included 104 lung cancer patients and 40 healthy individuals as controls. The permeability of the blood-brain barrier was evaluated using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The study analyzed the correlation between BBB permeability and both brain structure and cognitive function to determine the extent of BBB damage's influence on cognitive impairment. RESULTS: The study revealed a significant increase in BBB permeability among lung cancer patients, particularly in those experiencing cognitive impairment. Those with cognitive impairment exhibited a substantial decrease in cortical volume across several brain regions. Notably, the Ktrans value in the right superior parietal cortex was significantly elevated in the cognitive impairment group compared to both the non-cognitive impairment group and the healthy control group. CONCLUSION(S): The findings indicate a strong association between BBB damage and cognitive impairment in lung cancer patients. DCE-MRI has shown promise as an effective diagnostic tool for assessing BBB damage in the context of lung cancer treatment. This research contributes novel insights into the pathophysiological mechanisms underlying cognitive impairment in lung cancer patients and provides valuable information for the development of personalized therapeutic strategies.