Thyroid Dysfunction as a Prognostic Indicator for Overall Survival in Advanced Lung Cancer Patients Treated with PD-1/PD-L1 Inhibitors

Objective This study aims to explore the correlation between the occurrence of thyroid dysfunction (TD) and the overall survival (OS) of advanced lung cancer patients treated with PD-1/PD-L1 inhibitors, providing a basis for personalized diagnosis and treatment. Method The data of 60 patients who were initially diagnosed with advanced lung cancer at two hospitals in Shihezi, Xinjiang, China from January 2019 to August 2024 were retrospectively collected. The baseline thyroid function was normal. The patients were divided into TD and non-TD groups based on TD occurrence to analyze the correlation between TD occurrence and prognosis. Results The median OS was longer in the TD group than in the non-TD group (19.77 vs. 15.9 months), accompanied by a numerically lower risk of mortality (HR: 0.751, 95% CI (0.414–1.362), p  = 0.345). The 1-year OS rate of the TD group was numerically lower than that of the non-TD group (66% vs. 68%, RD (risk difference) = 0.02, NNT (number needed to treat) = 50). However, the 2- (45% vs. 24%, RD = -0.21, NNT = 5), 3- (30% vs. 12%, RD = -0.18, NNT = 6), and 4-year OS rates (30% vs. 12%, RD = -0.18, NNT = 6) were significantly higher than those of the non-TD group. There were differences in OS between different types of TD ( p  < 0.05). The patients with low-T3 syndrome had a significantly shorter OS compared with the non-TD group (5.4 vs. 15.9 months); thus, it was a risk factor for mortality (HR > 1, p  < 0.05). Compared with patients with other types of TD, patients with overt hypothyroidism and low-T3 syndrome had significantly shorter OS (11.92 vs. 28.13 months, 5.4 vs. 20.85 months), and they were also risk factors for mortality (HR > 1, p  < 0.05). Conclusion The occurrence of TD is positively correlated with the good prognosis of advanced lung cancer patients treated with PD-1/PD-L1 inhibitors, and the correlation becomes increasingly significant over time. There are also some differences in prognosis between different types of TD.