Recurrent Thyroid Cancer Best Detected by Ultrasound

Ultrasound tests performed in a doctor’s office may be more sensitive in detecting recurrence of the two most common types of thyroid cancer than the standard whole-body radioiodine scans and serum thyroglobulin tests, according to researchers at the University of Cincinnati (UC). The findings will be presented today at the American Thyroid Association’s 77th annual meeting (Oct. 11-15). The thyroid gland, located under the Adam’s apple in the front part of the neck, makes a hormone (thyroid hormone) that regulates metabolism.

Radioiodine imaging and serum thyroglobulin testing are the two most commonly used diagnostic procedures to detect thyroid cancer recurrence. A whole-body radioiodine scan is done by administering a small dose of radioactive iodine to determine if there are remaining thyroid cells that need to be destroyed. A serum thyroglobulin test is a blood test that measures the levels of thyroglobulin, a thyroid cell protein that serves as a thyroid cancer marker. "The primary limitation of thyroglobulin testing is that it's unreliable in many patients with thyroid cancer," says David Steward, MD, associate professor of otolaryngology at UC and director of thyroid and parathyroid surgery. "Ultrasound can identify certain features of lymph nodes to detect cancer without relying on just size," says Steward. "In other tests, like CT scans and MRI's, the size of the lymph nodes is important to determine if a tumour is benign or malignant." There are benefits to having an ultrasound performed in your doctor's office, according to Steward."Your doctor knows your medical history, and you don't have to make a separate appointment to see a radiologist for the test," he says. "Another advantage is that ultrasound is non-invasive, and patients don't have to undergo a special diet or preparation as they do with radioiodine scans. Ultrasound is also less expensive than other imaging tests," says Steward. The retrospective study consisted of 96 patients who had office-based neck ultrasounds during an 18-month period in UC's multidisciplinary thyroid cancer clinic. Twenty-two percent had recurrent thyroid cancer detected at a mean of seven years after initial treatment. The ultrasound correctly identified disease in 91 percent of patients whose cancer recurred. Serum thyroglobulin testing detected cancer in 68 percent of these patients, while radioiodine imaging correctly identified that disease had returned in only 20 percent. (Source: University of Cincinnati : October 2006.)