Most patients with thyroid cancer have no obvious clinical symptoms in the early stages and often present to the doctor with a painless neck lump or nodule. As the tumour increases in size, it may compress or invade adjacent organs or tissues, leading to breathing difficulties, difficulty in swallowing, jugular vein anger, hoarseness, flushing, tachycardia and other manifestations. Some patients may develop cervical lymph node metastases and distant organ metastases, mainly to the lungs, liver and bones.