Patients with RET‐mutant medullary thyroid cancer who had previously received vandetanib, cabozantinib, or both, the percentage who had a response was 69%, and 1‐year PFS rate was 82%. In 88 patients with RET‐mutant medullary thyroid cancer who had not previously received vandetanib or cabozantinib, the percentage who had a response was 73%, and 1‐year PFS rate was 92%. In 19 patients with previously treated RET fusion‐positive thyroid cancer, the percentage who had a response was 79%, and 1‐year PFS rate was 64%. Here, RET is linked to medullary thyroid gland carcinoma.