"Parameters of Body Composition as prognostic biomarkers in patients with RET-altered thyroid cancer treated with selpercatinib" Post-hoc analysis of the LIBRETTO-001 trial

Thyroid cancer is a growth of cells that starts in the thyroid. The thyroid is a butterfly-shaped gland located at the base of the neck, just below the Adam's apple. The thyroid produces hormones that regulate heart rate, blood pressure, body temperature and weight.
Thyroid cancer is the most common endocrine malignancy, affecting more women (with an age peak at 20 – 40 years) than men. It is the 9th most commonly occurring cancer worldwide. Medullary thyroid cancer (MTC) is a subtype of thyroid cancer, which is rare, only about 3-5% of the thyroid cancer cases; in 25% of cases, it is hereditary.

Low skeletal muscle mass (LSMM), meaning a low amount of muscle in the body, especially in the central parts, as assessed by sectional images such as computer tomographic (CT) scans has been measured in many research studies in the field of cancer. in thyroid cancer, LSMM seems to predict how the patients will cope with the disease and/or how well the respective treatment will work.

A new drug, selpercatinib, recently became available. It inhibits selectively the most important molecular “driver” (molecular pathology that makes the tumor grow) in MTC. This driver is called "rearranged during transfection" (RET). The treatment with this drug results in a very high probability for tumor regression (tumors decreasing in size) under the treatment and also few side effects.

The purpose of the present study is, as a first step to measure the muscle mass but also fat content on one slice of the abdominal CT using artificial intelligence.In a second step, we will analyze the connection of these parameters to the progression-free survival, overall survival, objective response rate (the percentage of patients who achieve a response) and treatment toxicity in patients with RET-altered thyroid cancer treated with selpercatinib. Furthermore, also parameters may be correlated with changes of body composition during the course of the study.