Case study examines spread of papillary thyroid cancer to bones

08/12/2011
Papillary thyroid cancer (PTC) is generally considered the most benign of all thyroid carcinomas, with a low risk of metastasis, which is one reason why a researcher from Georgetown University published a case study of a patient whose PTC was found to have spread to many skeletal sites in her body.

The report appeared in the latest issue of the Journal of Clinical Endocrinology and Metabolism. Dr. Jason Wexler of Georgetown's School of Medicine emphasized that this case is extraordinary for its rarity and direness, since PTC is relatively survivable and unlikely to spread.

PTC accounts for about 70 percent of all thyroid cancer diagnoses, according to the Columbia University Department of Surgery (CUDS).



The National Institutes of Health adds that approximately 95 percent of patients with PTC survive at least 10 years beyond their diagnosis.



Why, then, was the instance of PTC in the case study so serious? For one thing, Wexler believed that the patient had had cancer for some time without being aware of it. He wrote that the woman, who was 43 years old at the time of admittance, had undergone a partial thyroidectomy 25 years previously to treat a benign lump.

In the present day, a routine checkup detected a large tumor in one of the woman's neck lymph nodes. Subsequent radioactive iodine (I-131) imaging and computed tomographic scans revealed that the patient had extensive metastases in her lung, ribs, vertebrae and humerus. A biopsy established that these tumors had grown from migrated PTC cells.

Wexler estimated that only 1 to 7 percent of PTC cases involve bone metastases. How had this happened?

"I assume that (although I cannot prove) a diagnosis of thyroid cancer was missed at the time of her surgery in the past," the author theorized.

He then listed her treatments, which included a completion thyroidectomy, surgery to remove the lung tumor, I-131 injections, hormone therapy and doses of zoledronic acid to improve bone strength.

While the woman suffered a fracture due to skeletal weakening, her health stabilized and she is still alive, Wexler concluded.

He added that even though PTC migration automatically worsens the prognosis, the relative mildness of papillary thyroid carcinoma indicates that a person's chances of 10-year survival are still much higher than for more virulent forms of the disease, like anaplastic thyroid cancer.

Based on data provided by CUDS, the case study's patient has a 24 percent likelihood of surviving another 20 years.

Nearly 45,000 Americans are diagnosed with thyroid cancer every year, according to the National Cancer Institute.