When Is a Thyroid Cancer No Longer a Thyroid Cancer?
In April 2016, a group of physicians including pathologists (physicians who diagnose diseases by examining abnormal cells and tissues) along with endocrinologists and surgeons who also specialize in treating patients with thyroid disorders made a very important statement about thyroid cancer: Many cases previously diagnosed as thyroid cancer were not cancer after all. This declaration drew national and international attention and was reported in The New York Times among other media outlets. Many patients from among the more than half-million people in the U.S. with previously and recently diagnosed thyroid cancer contacted their physicians in order to find out what this meant for them. The complete report appeared in the April 2016 Journal of the American Medical Association—Oncology and was entitled “Nomenclature Revision for Encapsulated Follicular Variant of Papillary Thyroid Carcinoma: A Paradigm Shift to Reduce Overtreatment of Indolent Tumors.”
The purpose of this communication is to review this report, whom it applies to and what it really means for patients now.
What is thyroid cancer?
The thyroid gland is a small, butterfly-shaped gland that normally weighs less than an ounce and is located at the base of the neck below the larynx (voice box). The thyroid gland consists of two cell types: follicular cells and C-cells. The follicular cells are the dominant cells of the thyroid and make thyroid hormone that sets the pace of your metabolism, the chemical activity by which cells convert nutrients into energy. Thyroid cancer is a type of tumor or growth arising in the thyroid gland. Most thyroid growths termed thyroid nodules are not cancer. Cancerous tumors are those that may invade or grow within the thyroid or into the nearby tissues and organs or spread throughout the body.
How common is thyroid cancer?
About 60,000 new cases of thyroid cancer are expected to be diagnosed in the U.S. in 2016 with over two-thirds occurring in women. There are presently over 600,000 Americans who have been diagnosed with thyroid cancer.
Generally thyroid cancer is slow growing, rarely causes pain or disability, is easily treated, and may be cured with surgery alone. Despite its rising incidence, which is mostly due to more detection, the number of people dying from thyroid cancer per year in the U.S. has stayed about the same for many years, at around 2,000.
What are the most common types of thyroid cancer?
A majority of thyroid cancers arise from the follicular cells of the thyroid. Papillary thyroid cancer accounts for about 75 to 80 percent. Follicular thyroid cancers make up about 10 percent. Not only are these two types far and away the most common type of thyroid cancers arising from thyroid follicular cells, but they also generally carry the best prognosis and chance for cure.
Editor’s Note: The names of the different types of papillary and follicular thyroid cancers are similar sounding because they are all cancers arising from follicular cells, the hormone-producing cells of the thyroid
Which type of cancer was the new recommendation about?
It was about a type of papillary thyroid cancer that has been called “encapsulated follicular variant of papillary thyroid cancer” (EFVPTC). Encapsulated refers to the fact that it is fully surrounded by a capsule or a shell. ”Follicular variant” refers to the fact that the cells are arranged in groups that resemble normal thyroid cell groups. This type of cancer is now estimated to make up approximately 10 to 20 percent of all thyroid cancers.
What were the main points of the new recommendation?
- The group of expert physicians concluded that that EFVPTC was not a cancer
This was based on studying over 100 patients previously diagnosed with EFVPTC whose treatment was surgery alone – and in the majority of instances only limited to surgery. Before being included in the study, the patients’ diagnosis of EFVPTC was confirmed by a group of 24 thyroid pathologists who reanalyzed every case (some cases did not qualify). During at least 10 years of follow-up examinations, and in some cases over 20 years, no patient had evidence of cancer at any point after their initial treatment.
- Since EFVPTC did not behave like a “cancer” it should be renamed
The group proposed classifying these tumors “noninvasive follicular thyroid neoplasm with papillary-like nuclear features” (NIFTP). Neoplasm is a synonym for tumor, which in this case is benign. Noninvasive refers to the fact that even under a microscope the tumor was confined by the limits of its capsule, which remained intact or remains within its boundary. In case there is no capsule, a “circumscribed” or very well-defined tumor that does not extend beyond its very well-defined borders is also considered non-invasive. Papillary refers to the similarity some cells have features to what is seen in a typical papillary thyroid cancer
Why is this so important?
Less treatment and monitoring would be called for:
- Only surgery will be required to remove the tumor
- Limited surgery will be sufficient
- Radioactive iodine treatment will not be necessary
- Treatment with lower doses of thyroid hormone than what is typically prescribed for those with thyroid cancer may be appropriate
- Less follow-up and testing
Additionally, learning that one does not have cancer provides immense relief in the short term and eliminates the psychological burden one carries after being diagnosed with cancer.
Since NIFTP is not cancer, why does any surgery have to be done?
- Even though NIFTP does not appear to be cancer, some experts believe that over time it may progress to a cancer.
- There are no shortcuts to diagnosing NIFTP. It cannot be diagnosed by ultrasound, needle biopsy (AKA fine-needle aspiration or FNA), blood test or molecular analysis (see more information at: http://www.empoweryourhealth.org/magazine/vol7_issue1/doctor_what_do_you_mean_you_cant_tell_whether_i_have_thyroid_cancer). Most important, it must be distinguished from invasive forms. This can only be achieved after the tumor is completely surgically removed. Doing so enables the thyroid pathologist to study enough pieces of the tumor in order to make sure that the entire capsule and vessels surrounding it do not contain any tumor. NIFTP then is not a diagnosis that can be made from a needle biopsy. Surgery has to be done to obtain this diagnosis.
What should and can those with previously diagnosed EFVPTC do to find out if they had or have thyroid cancer?
Recently diagnosed cases require careful review of the entire tumor by a pathologist familiar with how to diagnose NIFTP. If the diagnosis of EFVPTC was made over a decade ago and there has never been any evidence of cancer following initial therapy, re-examination of the original pathology may not be necessary. Review of other cases should be discussed with your physicians and considered on a case-by-case basis, keeping in mind that in many cases there may not be enough material available to be able to carefully re-analyze it.
What don’t we know about NIFTP?
Although the recommendations were based on strong grounds, the study that served as the basis for the reclassification was a relatively small one, involving just over 100 cases. Some studies have reported similar findings but clearly additional studies over time will be required to confirm the reported findings.
What questions remain?
- Will the criteria for diagnosing NIFTP be universally adopted and accurately employed by pathologists throughout the USA who diagnose thyroid cancer?
- Will the new recommendations affect the way physicians care for patients with thyroid cancer?
- Over the long-term will patients benefit from these recommendations?