Afirma and Cytologically Benign Thyroid Nodules Show Comparable Clinical Behavior

With Trevor E. Angell, MD, and Louise Davies, MD

Thyroid cancer, words related to thyroid nodules and cancerIn a retrospective analysis of 95 consecutive cytologically indeterminate (Cyto-I) or Afirma (Veracyte, Inc.) gene-expression classifier benign (GEC-B) thyroid nodules, only one malignancy was detected over a median follow-up of 13 months.

The findings suggest that Cyto-I/GEC-B nodules shows comparable clinical behavior to cytologically benign nodules and may be conservatively monitored, the authors concluded in the Journal of Clinical Endocrinology and Metabolism.

“These data further demonstrate the appropriateness of monitoring cytologically indeterminate, Afirma GEC-B nodules without surgical resection, much in the same way a physician would monitor a cytologically benign nodule,” said lead author Trevor E. Angell, MD, Associate Physician in the Division of Endocrinology, Diabetes, and Hypertension at Brigham and Women's Hospital, and Instructor in Medicine, Harvard Medical School, Boston, Massachusetts.

“Our research addresses an important gap in our knowledge as it evaluates if it is indeed acceptable to monitor patients with cytologically indeterminate-Afirma GEC benign thyroid nodules nonoperatively,” Dr. Angell explained.

Watchful Waiting: Median Follow-up Was 13 Months

Dr. Angell and colleagues examined the outcomes of 95 Cyto-I/GEC-B nodules in 90 patients, five of whom underwent surgical resection. Of the remaining 90 nodules, 58 (64.4%) in 56 patients were reevaluated using ultrasound after a median of 13 months (range, 4-40 months). An additional 8 Cyto-I/GEC-B nodule patients underwent surgical resection during follow-up (median, 9 months).

Cyto-I/GEC-B nodules showed similar growth compared to 1224 Cyto-B nodules using the two main outcome measures: ≥20% in 2 dimensions (8.6% vs. 8.3%, P=0.80) or ≥50% in volume (17.2% vs. 13.8%, P=.44). The Cyto-I/GEC-B group had a higher rate of thyroidectomies (13.8% vs. 0.9%, P<.0001), and 1 patient was found to have cancer (minimally-invasive follicular thyroid carcinoma), with no evidence of persistent disease after initial treatment.

“It is clinically important to note that the one case of thyroid cancer that was found during follow-up was very low-risk and successfully treated with initial therapy, suggesting that any potential delay in diagnosis did not result in additional harm to the patient,” Dr. Angell said.

Clinical Outcomes and Implications based on Follow-Up

“The clinical use of the Afirma gene-expression classifier continues to grow based on the robust validation trial data published in the New England Journal of Medicine, showing that it improves the preoperative diagnosis of thyroid nodules with indeterminate cytology,” Dr. Angell said.1 “However, there were few data regarding the outcomes of thyroid nodules with benign GEC results,” Dr. Angell continued.

“In this study, we report the outcomes and long-term follow-up of patients with such nodules and demonstrate for the first time that indeterminate nodules with a benign Afirma result show similar growth and ultrasound characteristics to cytologically benign nodules during follow-up,” Dr. Angell said. “Furthermore, when such nodules are resected, they prove rarely malignant. These data strongly suggesting that non-surgical management for such nodules is appropriate,” Dr. Angell concluded.

Benign Findings on Afirma GEC Testing Offers Reassurance

The study findings suggest that “benign readings by the Afirma GEC should be generally considered reassuring for patients and clinicians alike,” commented Louise Davies, MD, Associate Professor of Surgery at Geisel School of Medicine at Dartmouth, Hanover, NH, and at The Dartmouth Institute for Health Policy & Clinical Practice, Lebanon, NH. She also is on faculty with the VA Outcomes Group, White River Junction, VT.

“Among those undergoing an operation, one of 13 patients turned out to have cancer, which translates to about 7%,” Dr. Davies said. “While some people may find that rate to be high, it is lower than the rate would likely be if the cytologically indeterminate nodules were removed without doing the Afirma GEC test—suggesting the test does effectively weed out neoplastic nodules,” Dr. Davies said.

In reference to the 1 case of cancer detected in this study during follow-up, Dr. Davies does not consider follicular thyroid carcinoma to be a low-risk malignancy, but did agree that “close ultrasound follow-up provided to this person suggested a change in the nodule that made surgery advisable, and that the decision for surgery was a good one.”

Dr. Davies added that most thyroid malignancies detected using follow-up testing will never cause harm to the patient. However, she added, “if we can save people from unnecessary surgery for what turn out to be benign nodules, then we have provided the patients a service, and this study should reassure patients and clinicians that cytologically indeterminate/Afirma GEC-B nodules are quite likely to be just that.”

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