As the public becomes more health conscious and medical checkups become more popular, the incidence of thyroid nodules is increasing. Ultrasound examinations can detect nodules in the thyroid gland in about 20% or more of normal people. They are more common in women than in men, and in middle-aged and older people than in teenagers. Despite the high incidence of thyroid nodules, the majority of them are benign and only 5% are malignant. So there is nothing to worry about. The difference between benign and malignant thyroid nodules can be made from the following aspects. Age and gender: Although the incidence of thyroid nodules is higher in women than in men, the incidence of thyroid cancer in men is 2-3 times higher than in women, and 50% of thyroid nodules appearing in childhood are malignant, so men, children and senior age are three groups that should be careful if thyroid nodules are found! 2. Medical and family history: If the head and neck were previously treated with radiation therapy, there is a higher chance of malignant lesions in the thyroid gland; also, if immediate family members have medullary thyroid cancer or multiple endocrine tumors, there is a higher chance of malignant tumors in the thyroid gland. 3. Growth rate of nodules: Fast-growing nodules suggest cancer, but some patients suddenly find that their thyroid nodules have grown significantly after coughing or sudden exertion, which is mostly caused by bleeding within the adenoma, not cancer. 4. Texture of nodules: A soft, smooth nodule that can be pushed by hand is mostly benign. A hard, fixed, painless nodule has a high chance of malignancy (but there are exceptions). 5. Thyroid nodules causing significant pressure symptoms (difficulty in breathing or swallowing) or hoarseness should be treated surgically. 6.B ultrasound examination: irregular shape, gravel-like calcification, blood flow disturbance, and transverse diameter larger than longitudinal diameter should be beware. 7. Lymph node metastasis in the neck: if there is a thyroid nodule on one side and the lymph nodes in the neck on the same side are enlarged and hard, cancer should be considered and lymph node metastasis has occurred. 8.There are also some special tests to identify thyroid nodules such as nuclear scan and calcitonin, which have some reference value to identify the benignity and malignancy of the nodules. 9.Invasive tests such as fine needle aspiration can be used for qualitative diagnosis from pathology and cytology. Even if it is thyroid cancer, there is no need to worry too much because more than 90% are papillary thyroid cancer, which is the most “benign” tumor among all cancers, and as long as timely and correct surgery is performed, it will not affect the life expectancy too much.