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New Thyroid Nodule Test May Help Eliminate Unnecessary Surgery

Galectin-3 Test Can Help Confirm Nodule Malignancy


Updated June 17, 2014

A conservative estimate is that as many as 5% of adults (an estimated 15 million Americans) have thyroid nodules -- lumps or growths located in the thyroid gland. Most of these nodules are non-cancerous (benign). In 2007, an estimated 30,200 cases of thyroid cancer were diagnosed.

Determining which nodules are cancerous is a challenge that typically falls to endocrinologists. Endocrinologists typically evaluate nodules with radioactiove uptake scans, ultrasound, and blood tests.

Those nodules that remain suspicious are evaluated by a procedure known as fine-needle aspiration (FNA) biopsy. Cells are removed and then evaluated to see if they are cancerous (malignant).

When an FNA biopsy is conducted, an estimated 70% of nodules are FNA are found to be benign. Cancer is definitively found in an estimated 5% of nodules. The remainder are considered suspicious, meaning that the sample wasn't conclusive or was inconclusive, meaning sampling wasn't sufficient or analysis wasn't able to be performed.

Typically, with suspicious or inconclusive nodules, patients are referred for surgery and, in most cases, the nodule, lobe, or entire thyroid gland is then removed. The nodule is then thoroughly analyzed for evidence of cancer.

After surgery and analysis, about 85% of suspicous or inconclusive nodules turn out to be benign. This means that a fairly large number of patients are having surgery that -- while considered to be the only conclusive way to rule out thyroid cancer -- is actually unnecessary.

Hope For Preventing Unnecessary Surgeries?

A new procedure described in the May 19, 2008 issue of The Lancet Oncology may help reduce unnecessary thyroid surgeries to evaluate nodules. By testing suspicious thyroid nodules for the expression of a molecule called galectin-3, experts can help identify malignant thyroid nodules without surgery.

About the Study

The aim of the research was to determine if measurement of a molecule called galectin-3 could help distinguish between benign and malignant thyroid nodules. Galectin-3 was chosen because it is not found in a healthy thyroid cell, but can be found in cancerous thyroid cells. In the study, Italian researchers looked at 465 subjects who had inconclusive thyroid nodules that were greater than 1 cm in size. Galectin-3 was tested, and then the nodules were removed and analyzed for cancer. The researchers found:
  • 331 (71%) of the inconclusive nodules did not express galectin-3, and 280 (85%) of these galectin-3-negative nodules were benign
  • 134 of 465 (29%) inconclusive nodules did express galectin-3. Of these, 101 (75%) were confirmed as malignant.
The overall sensitivity of the galectin-3 test was 78%, and the test's positive predictive value was 82%; negative predictive value was 91%. The test did, however, miss 22% the cancers.

According to the study authors: "The galectin-3 method proposed here does not replace conventional FNA-cytology, but represents a complementary diagnostic method for those follicular nodules that remain indeterminate. The correct approach for this preoperative characterization of thyroid nodules always needs careful multidisciplinary assessment of each patient, according to published guidelines."

What This Means for Patients

It's not likely that endocrinologists will be using the galectin-3 testing anytime soon, but it may eventually become part of the evaluation process for nodules, done as an additional test along with the FNA biopsy. It could be of particular use in confirming a potential cancer suspicion in an inconclusive nodule, which would then help both patient and doctor move forward in a timely manner to schedule a surgery and follow-up treatments.

It's not clear, however, what ultimate benefit there will be for patients who have an inconclusive FNA and a negative galectin-3 if the galectin-3 test is missing 22% of cancers. Because, for those patients, a surgical evaluation will still be the only way to positively rule out thyroid cancer.

In the meantime, patients with inconclusive thyroid nodules may want to consider obtaining a second opinion from a pathologist with expertise in evaluating thyroid biopsy results.

More Information on Thyroid Nodules

Bartolazzi Armando, et. al. "Galectin-3-expression analysis in the surgical selection of follicular thyroid nodules with indeterminate fine-needle aspiration cytology: a prospective multicentre study," Lancet Oncology DOI:10.1016/S1470-2045(08)70132-3 Online
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