While a fine-needle aspiration biopsy is the standard test for determining whether a thyroid nodule is cancerous, the biopsy is not necessary for all nodules, according to MedicineNet. The more nodules on the thyroid and the "hotter" the nodule looks on a scan, the less likely the nodule is to be cancerous.
When doctors find a nodule on the thyroid, they often go over the patient's medical history and conduct a physical examination to determine how likely the nodule is to be cancerous before suggesting a fine-needle aspiration biopsy, explains MedicineNet. A variety of factors, including whether the patient is male or female, the patient's age and how much exposure the patient has had to radiation, influence the likelihood that the nodule is cancerous. If the nodule is hard and doesn't move when the doctor examines it, or if the patient has symptoms such as a hoarse voice or problems with swallowing, the chances that the nodule is malignant are increased. A history of thyroid cancers in family members may also prompt a doctor to ask for a biopsy.
Medical experts believe about half of all people have bumps on their thyroids, many without ever experiencing symptoms. Most nodules are non-cancerous, and so doctors do not ask for a biopsy if the patient is at low risk. If the doctor does decide the fine-needle aspiration biopsy is needed, it takes about 20 minutes and can be done on an out-patient basis in the doctor's office. Results of the biopsy are typically available about a week after the procedure is done, according to MedicineNet.