Study Calls for Reclassification of Thyroid Tumors as Non-Cancerous

A new study is calling for a change in name for certain thyroid tumors. Patients diagnosed with what is currently known as noninvasive encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) have a very low risk for recurrence and therefore, researchers led by Yuri E. Nikiforov, MD, PhD, of the University of Pittsburgh, have suggested renaming the condition noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).

“This study was undertaken to re-examine the clinical and pathologic approach to noninvasive EFVPTC-a thyroid tumor that, despite increasing evidence of its indolent behavior, is nonetheless classified as cancer,” Nikiforov and colleagues wrote in JAMA Oncology. “The outcome data obtained in this study support renaming this tumor in a manner that more accurately reflects its behavior.”

According to the study, the recent increase in the diagnosis of thyroid cancer is due mainly to diagnosis of papillary thyroid carcinoma, particularly FVPTC. A diagnosis of EFVPTC currently accounts for between 10% and 20% of all thyroid cancers diagnosed in Europe and North American. However, studies have shown that FVPTC, specifically, EFVPTC, is indolent and distinct from other invasive thyroid cancers.

With this study, Nikiforov and colleagues wanted to convene experts to examine if EFVPTC is in fact a cancer or if it should be reclassified.

To do this, Nikiforov and colleagues conducted a study of patients with thyroid nodules diagnosed as EFVPTC, including 109 patients with noninvasive EFVPTC followed for between 10 and 26 years and 101 patients with invasive EFVPTC followed for between 1 and 18 years. Twenty-four pathologists reviewed digitized histologic slides taken from these patients and then convened to establish consensus diagnostic criteria and develop new nomenclature.

The review revealed that all 109 patients with noninvasive EFVPTC were alive and had no evidence of their disease at their final follow-up, which occurred at a median of 13 years after diagnosis. Looking at those patients with invasive disease, five patients went on to develop distant metastases and two died of the disease.

Based on the outcomes seen among patients with noninvasive EFVPTC, the experts came up with the name noninvasive follicular thyroid neoplasm with papillary-like nuclear features-or NIFTP. According to the study, these tumors would have the following characteristics:

• main morphological features, ie, the follicular growth pattern and nuclear features of PTC;

• lack of invasion, which separates this tumor from invasive EFVPTC;

• clonal origin determined by finding a driver mutation, which indicates that the lesion is biologically a neoplasm; and

• a very low risk of adverse outcome when the tumor is noninvasive.

In an editorial published with the study, Kepal N. Patel, MD, of the Thyroid Cancer Interdisciplinary Program at NYU Langone Medical Center, pointed out that “the change in nomenclature could affect the clinical care and management of more than 45, 000 patients worldwide per year.”

In addition, he wrote: “By removing the word cancer, the term NIFTP acknowledges the low malignant potential of these tumors. This will potentially affect the way the disease is viewed by caregivers and patients. It will eliminate the psychological impact of receiving a cancer diagnosis. Furthermore, the new designation recognizes the appropriate biological behavior of this tumor and should decrease the overtreatment that the term cancer often breeds.”