Thyroid cancer symptoms are as follows: 1. Thyroid cancer is a malignant tumor occurring in the thyroid gland, the symptoms often do not have any manifestation in the early stage, i.e. it is not visible and not palpable in the early stage, and it is often discovered unintentionally through regular physical examination by ultrasound, which is also its scary point; 2. With the development of thyroid cancer, certain symptoms can appear, and as the tumor increases, it can be palpable in the neck and move up and down with the swallowing activity. It is characterized by hard texture and relatively fixed position, which is not easy to be pushed; 3. With the development of tumor, it may compress the surrounding organs or tissues, for example, compression of trachea may cause difficulty in breathing, compression of nerve may cause hoarseness, if compression of vagus nerve, Horner syndrome may appear on one side, i.e. droopy eyelid on one side, restricted sweat secretion on one side of facial skin, etc.; 4. If the tumor develops further, lymph node metastasis may occur, spreading to the surrounding lymph nodes, and enlarged lymph nodes can be palpated throughout the neck. If the tumor metastasizes to the whole body and metastasizes to the brain and lungs, corresponding complications in the brain and lungs will occur. 5. There is another type of thyroid cancer called medullary carcinoma, which is a special type of malignant tumor of the thyroid gland that can secrete a hormone and cause symptoms such as flushing and diarrhea.