GDF6 and thyroid cancer: Among the thyroid cancer, prognosis-related genes associated with differential CALCA expression, CNTFR, PRLR, TSLP, GDF6, and CD27 were significantly enriched in the cytokine–cytokine receptor interaction pathway, and high CALCA expression was significantly associated with the cytokine–cytokine receptor interaction pathway, neuroactive ligand-receptor interaction pathway, and cell-adhesion molecules, which suggests that these pathways may be involved in the development of thyroid cancer and could affect the prognosis of MTC patients.