Effect of Pre-Existent Sarcopenia on Oncological Outcome of Advanced Thyroid Cancer Patients Treated with Tyrosine Kinase Inhibitors

Simple Summary Data regarding the effect of pre-existent sarcopenia on the oncological outcome of advanced thyroid cancer patients treated with tyrosine kinase (TKI) are still lacking. The aim of the study was to investigate the prevalence of pre-treatment sarcopenia in Caucasian patients affected by advanced thyroid carcinoma and the impact of this condition on the response to TKIs treatment. Pre-treatment sarcopenia was found in 20.7% of patients, with an increase of up to 38.5% after 12 months of TKI therapy. Pre-treatment sarcopenia significantly affected treatment outcome, emerging as the parameter that has the greatest impact on Progression Free Survival. Sarcopenia might be used as a prognostic factor of TKI treatment outcome and the prevention of this condition, ideally before starting anticancer treatment, could be the strategy to obtain a better efficacy of therapy. (1) Background: Sarcopenia is associated with poor survival and treatment outcomes in several human cancers. The aim of the study was to investigate the prevalence of sarcopenia in a cohort of 58 Caucasian patients with advanced thyroid cancer before and during TKI treatment. The impact of this condition on the outcome of patients was also evaluated. (2) Methods: Sarcopenia was evaluated using the Skeletal Muscle Index (SMI). (3) Results: Pre-treatment sarcopenia was found in 20.7% of patients and this condition significantly affected treatment outcome, emerging as the parameter that has the greatest impact on Progression Free Survival (PFS) (HR 4.29; 95% CI, 1.21-15.11, p = 0.02). A significant reduction in SMI values was observed 3 (p = 0.002) and 12 months (p < 0.0001) after TKI treatment. At a 12-month follow-up, sarcopenia prevalence increased up to 38.5%. Here, 12-month sarcopenia was predicted by a lower SMI (p = 0.029), BMI (p = 0.02) and weight (p = 0.04) and by the presence of bone metastases (p = 0.02). (4) Conclusions: This is the first study that evaluated sarcopenia prevalence and its change over time in Caucasian patients with advanced thyroid cancer under TKI therapy. Sarcopenia seems to be a prognostic factor of TKI treatment outcome, suggesting the importance of the assessment of the nutritional status and body composition in advanced thyroid cancer patients.