Introduction: A low fT3/fT4 ratio has been associated with a poorer prognosis in patients treated for different solid malignancies. However, the prognostic role of baseline thyroid function in patients with metastatic urothelial carcinoma (mUC) has not yet been established.
Patients and methods: We analyzed 72 consecutive immunotherapy-treated patients with mUC from a single institution. We recorded clinical data, baseline blood test results, and oncological outcomes. We stratified patients into three groups according to the fT3/fT4 ratio value and analyzed differences in progression-free survival (PFS), overall survival (OS), and radiological response in the three groups. We also conducted univariate and multivariate analyses to identify prognostic factors for PFS and OS.
Results: The median PFS in the low, intermediate, and high fT3/fT4 ratio groups was 2.2, 4.1, and 8.2 months, respectively (P < 0.01). The median OS in the low, intermediate, and high fT3/fT4 groups was 3.6, 10.3, and 19.1 months, respectively (P < .01). The low fT3/fT4 ratio maintained its prognostic role independently of other prognostic factors. Patients with a high fT3/fT4 ratio had an increased radiological response.
Conclusion: Thyroid hormone impairment, as measured by the fT3/fT4 ratio, is a strong prognostic factor in patients treated with immunotherapy for urothelial carcinoma.
Keywords: Bladder carcinoma; Deiodination; Immune checkpoint inhibitors; Urothelial carcinoma; fT3/fT4.
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