Thyroid cancer develops in the thyroid, a butterfly-shaped gland located at the base of the neck. When cells in the thyroid change and grow abnormally, they can form a tumor. While many thyroid nodules are non-cancerous, early detection of cancerous ones is important for effective treatment and improved outcomes. Identifying thyroid cancer involves various diagnostic tests.
Initial Medical Evaluation
When thyroid cancer is suspected, the diagnostic process often begins with a thorough medical evaluation. A doctor performs a physical examination of the neck, checking for lumps, nodules, or enlarged lymph nodes. Asking the patient to swallow helps assess the movement of any thyroid abnormalities.
Medical history and reported symptoms also play a role. Patients may report a neck lump, voice changes, difficulty swallowing, persistent cough, or neck pain. These symptoms, though common, warrant investigation if thyroid cancer is suspected.
Blood tests are also part of the initial evaluation. Thyroid Stimulating Hormone (TSH) levels are checked, as abnormal levels can be associated with thyroid nodules. While TSH levels are usually normal in thyroid cancer, they can guide further imaging. For specific types, like medullary thyroid cancer, calcitonin levels may be measured to indicate its presence. However, calcitonin testing is not a routine screening for all suspected thyroid cancers.
Imaging Studies
Medical imaging provides a detailed view of the thyroid and any abnormalities. Ultrasound is the primary imaging test for evaluating thyroid nodules. This non-invasive technique uses sound waves to create images, revealing nodule size, number, and location.
Ultrasound can also assess various characteristics of the nodules that help determine their potential nature. Features like whether a nodule is solid or fluid-filled, its echogenicity, margin regularity, and the presence of microcalcifications are evaluated. Microcalcifications, for instance, are often associated with a higher likelihood of malignancy.
Other imaging tests, such as CT, MRI, or PET scans, are not typically used for initial thyroid nodule diagnosis. These methods may be employed after a cancer diagnosis to assess disease extent, determining if cancer has spread to lymph nodes or distant body parts.
Biopsy and Confirmation
Fine Needle Aspiration (FNA) biopsy is a definitive step in diagnosing thyroid cancer. This procedure uses a thin, hollow needle to collect cells directly from a suspicious thyroid nodule. Ultrasound guides the FNA, allowing precise targeting and adequate cell collection.
Once collected, the cell samples are sent to a laboratory where a pathologist examines them under a microscope. The pathologist classifies the results, often using a standardized system, categorizing them into groups like benign (non-cancerous), malignant (cancerous), or indeterminate.
A benign result indicates the nodule is not cancerous, leading to continued monitoring. Indeterminate results show concerning features but are not definitively cancerous, often requiring repeat FNA or further testing. If results are suspicious or malignant, cancer is strongly suggested, and surgical removal is often recommended. If FNA results are inconclusive, a surgical biopsy, involving removal of part or all of the thyroid, may be performed for a definitive diagnosis.