A sequencing test can predict which thyroid nodules are cancerous and require surgical removal—reducing the need for multiple invasive diagnostic procedures.
In up to 80 percent of cases, examination of cells collected with a fine needle from a suspicious lump in the thyroid, a gland in the front of the neck, typically can tell a pathologist whether it is benign or malignant, says lead investigator Yuri Nikiforov, professor of pathology and director of the University of Pittsburgh School of Medicine’s Division of Molecular and Genomic Pathology.
“However, in 20 percent of cases, the result is indeterminate, meaning we can’t say for certain whether the nodule is cancerous,” he says. “That means the patient might have a repeat needle biopsy, or will go to the operating room to have the affected thyroid lobe removed for further assessment. If it turns out to be cancer, the patient has to have yet another surgery to have the rest of the thyroid taken out.”
Three-quarters of such diagnostic surgeries are performed on what turn out to be benign nodules. Such patients could have avoided surgery if physicians were confident without surgical excision that the nodules are very likely to be harmless.
In the new study, the researchers used the latest version of the test they developed, called ThyroSeq v2.1, to look for more than 300 cancer-associated mutations in 56 genes using cells obtained from fine-needle aspiration biopsies in more than 440 patients. Of that group, 96 patients had established diagnoses through surgery, allowing the team to assess ThyroSeq’s predictive power.
The team found the test was able to correctly classify 20 out of 22 cancers with high precision and accuracy. Most importantly, when the test was negative, the residual risk of cancer in those nodules was so low that surgical excision was not needed.
“We finally have a test that offers high accuracy in predicting whether a nodule is cancerous or if it is benign,” says Nikiforov.
“This molecular testing panel holds great promise for streamlining and eliminating unnecessary surgery, not just here, but nationwide,” says coauthor Sally E. Carty, professor and chief of endocrine surgery at Pitt School of Medicine. The test is available to and used by thyroid clinics around the country.
“Thyroid cancer now is the fifth most common cancer diagnosed in women, and it is one of the few cancers that continues to increase in incidence,” she notes. “It’s important to get to the diagnosis quickly and correctly.”
The University of Pittsburgh and the Richard A. & Leslie A. Snow Fund for Thyroid Cancer Research supported the work, which appears online in the journal Thyroid.
Source: University of Pittsburgh