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PHOENIX -- Genetic profiling of biopsies that can't be labeled benign or malignant on cytology testing may eventually diminish the number of surgeries needed, researchers reported here.
About half (48%) of the samples deemed suspicious on molecular testing in an office-based setting turned out to be malignant on the final pathology assessment after surgery, reported Brian Michael, MD, of Wellspan Endocrinology in Gettysburg, Pa., and colleagues during a presidential oral presentation session at the American Association of Clinical Endocrinologists meeting.
Action Points
- This study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- Genetic profiling of biopsies that can't be labeled benign or malignant on cytology testing may eventually diminish the number of surgeries needed.
- Point out that the study was limited because the researchers didn't have enough data to establish a false-negative rate for the technique.
"Use of [genetic analysis] should translate into fewer surgeries, decreased patient morbidity, and lower systemic costs," Michael said during the session.
Thyroid nodules are common in adults, but only a small fraction are malignant. Fine-needle aspiration (FNA) biopsy has been the most sensitive and specific tool for diagnosis, but 10% to 30% of samples done this way are not clearly benign or malignant.
Typically, these "indeterminate" nodules are referred to surgery, although only a quarter turn out to be malignant.
Some endocrinologists, however, have been adding an extra step of genetic analysis of the tumor in order to better determine which of these patients can avoid surgery.
Michael and colleagues looked at pooled data from three practices that have been doing genetic testing of indeterminate biopsies: one in Pennsylvania, one in Florida, and one in Texas. These practices had used the Afirma test by Veracyte during the first 18 months that it had been approved.
Together, the centers screened 750 thyroid nodules in 653 patients, and all biopsies had been done using FNA. Only the indeterminate samples -- a total of 17.8% of all samples -- had genetic evaluation.
Among these, 50% were suspicious, 46.75% were benign, and 3.25% yielded insufficient genetic material.
Of patients with suspicious markers who were referred for surgery, 48% had malignancy confirmed on final pathology.
"Half of patients in the indeterminate group previously referred for surgery can now be observed," Michael said. "Using [molecular testing] in a community practice environment results in a reduction in the number of surgeries required in patients with indeterminate cytology results."
The study was limited because the researchers didn't have enough data to establish a false-negative rate for the technique.
Still, they concluded that genetic testing may be able to significantly reduce the number of surgeries in patients with indeterminate cytology results.
Farhad Zangeneh, MD, an endocrinologist in Washington, DC, who was not involved in the study, said his practice uses the technique.
"You can reduce the number of patients referred for diagnostic surgery, and it allows the indeterminate [screen] to become a little less grey and more black or white," he said. "But just like a single biopsy, it's not 100%."
Zangeneh said he works with patients to determine their course of treatment using the molecular data.
"If the patient says, 'Even if you're comfortable with it, I still want surgery,' I arrange that. If the patient is conservative and says 'Can you follow it?', we do it," he said. "It boils down to, what [is the patient] comfortable with, what am I comfortable with, and then I make the decision with [a patient's] wishes, interests, and personality taken into account."
He added that some insurances do not yet cover molecular testing, although some researchers have argued that diagnostic surgery, which ranges from $12,000 to $15,000, is far more costly than the testing itself.
Disclosures
The researchers reported relationships with Genzyme and Labcorp.
Primary Source
American Association of Clinical Endocrinologists
Source Reference: Michael B, et al. "An office based evaluation of gene expression classifier use in thyroid nodules" AACE Meeting 2013;abstract 1038.