Age, tumor size affect metastasis, prognosis for patients with follicular thyroid cancer

Though it is not the most virulent form of thyroid carcinoma, follicular thyroid cancer (FTC) is more likely than the papillary variety to spread to distant sites in the body, which is one reason why Japanese researchers recently analyzed the factors affecting the metastasis of FTC.

Their results, which appeared in the journal Thyroid, indicated that the disease's likelihood of spreading beyond the thyroid can be most accurately predicted based on a patient's age, the size of their tumor and its invasion into the gland.

Surgeons and diagnostic pathologists from Japan's Ito and Keio University Hospitals came to this conclusion after analyzing the health records of 134 patients treated for FTC between 1989 and 1997.

In all, 36 participants were diagnosed with distant metastases of FTC, 13 during their partial or full thyroidectomies and 23 at their follow-up visits, which often occurred more than a decade later.

Though papillary thyroid cancer (PTC) and FTC are the two most common types of thyroid carcinoma, there are crucial differences between the two disease types. Essentially, FTC is less common and somewhat more serious.

PTC accounts for 80 percent of all thyroid cancer diagnoses, with FTC comprising a further 10 percent, according to the Weill Cornell Medical College Department of Surgery.

Depending on its stage at diagnosis, FTC has a 10-year survival rate between 95 and 43 percent, the department adds.

In the new study, researchers found that the risk of metastasis - and consequently, the 10-year survival rate - depended significantly on age, tumor size and extent of invasion.

The group said that patients who were less than 45 years old, had a tumor smaller than four centimeters across or had a minimally invasive variety of FTC had the best overall prognoses.

FTC is relatively survivable, as is PTC. In his book Could It Be My Thyroid?, Dr. Sheldon Rubenfeld estimates that, given proper treatment, 90 percent of patients with these varieties of thyroid cancer will survive.