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.