Correlation of Degree of Hypothyroidism With Survival Outcomes in Patients With Metastatic Renal Cell Carcinoma Receiving Vascular Endothelial Growth Factor Receptor Tyrosine Kinase Inhibitors

BackgroundHypothyroidism is a common adverse effect of vascular endothelial growth factor receptor tyrosine kinase inhibitor (VEGFR-TKI) therapy in patients with metastatic renal cell carcinoma (mRCC). Some studies have shown an association with improved survival. However, hypothyroidism severity has not been correlated with survival outcomes. We report the incidence and severity of VEGFR-TKI therapy-associated hypothyroidism in correlation with the survival outcomes of patients with mRCC.Patients and MethodsA retrospective analysis of patients with mRCC who received VEGFR-TKIs (2004 through 2013) was conducted from a single institutional database. Hypothyroidism, progression-free survival (PFS), and overall survival (OS) were assessed. Univariate and multivariate analyses were performed using the Kaplan-Meier method and Cox proportional hazard models.ResultsOf 125 patients with mRCC, 65 were eligible. Their median age was 59 years (range, 45-79 years), and 46 (70.8%) were male. Hypothyroidism occurred in 25 patients (38.5%), of whom 13 had a peak thyroid-stimulating hormone (TSH) level > 10 mIU/L during treatment. The median OS was significantly longer in patients with a peak TSH > 10 mIU/L than in patients with a peak TSH of ≤ 10 mIU/L (not reached vs. 21.4 months, P = .005). On multivariate analysis, risk criteria, number of previous therapies, and severe hypothyroidism (TSH > 10 mIU/L) during VEGFR-TKI therapy remained significant for improvements in PFS and OS.ConclusionThe severity of VEGFR-TKI therapy-associated hypothyroidism (TSH > 10 mIU/L) was associated with improved survival outcomes in patients with mRCC and should not necessitate a dose reduction or therapy discontinuation.