Prognostic Value of Thyroid Hormone Ratios in Patients With Advanced Metastatic Colorectal Cancer Treated With Regorafenib: The TOREADOR Study

Background The impact of free triiodothyronine (FT3)/free thyroxine (FT4) ratio on survival in hospitalized geriatric patients was recently described. Up today, there are no data regarding the prognostic role of FT3/FT4 ratio in patients with advanced cancer. We evaluated the impact of FT3/FT4 ratio on survival in patients with refractory colorectal cancer (CRC) treated with regorafenib. Methods Patients with metastatic CRC treated with regorafenib with available clinical data and baseline measurement of FT3, FT4, and thyroid-stimulating hormone (TSH) were considered eligible. Exploratory analyses included subjects treated at Istituto Oncologico Veneto. A confirmatory analysis was planned based on FT3/FT4 ratio tertile results, and a validation cohort was built on data retrieved from University of Cagliari. Results In an exploratory cohort, the median overall survival in patients with low, intermediate, and high FT3/FT4 ratios, according to tertiles' value, was 4.8, 5.0, and 7.6 months, respectively (P = .003). The differences were significant in the multivariate model (hazard ratio, 0.43; 95% confidence interval, 0.28-0.68; P = .0003). Confirmatory results were obtained in a validation cohort, both in univariate (P = .0002) and in multivariate (hazard ratio, 0.56; 95% confidence interval, 0.36-0.88; P = .0118) models. Conclusions High baseline FT3/FT4 ratio is strongly associated to better outcome in patients with progressive metastatic CRC treated with regorafenib. Further investigations are ongoing to draw definitive conclusions regarding a potential predictive effect.