A molecular diagnosis gives doctors and patients better treatment options when suspicious lumps are found in the neck.
Genetic biopsy: A Veracyte technician tests 142 genes from patients with suspicious nodules in their thyroid glands.
Later this year, doctors in the U.S. will be able to use a gene test to guide thyroid cancer surgery. The test helps determine when patients harbor a particularly dangerous form of the disease, which can require surgeons to do a second operation on top of the initial diagnostic procedure. Knowing that a patient has this particular form of thyroid cancer could enable surgeons to instead do a single, more extensive surgery.
The company behind the test, Veracyte, already sells a unique genetic assay that helps doctors decide whether to perform surgery on thyroid cancer patients at all. Thyroids that are not cancerous are often removed, which means unnecessary surgery and lifelong hormone replacement therapy for some patients.
Both tests are part of a broader movement in recent years to bring genetic tests into medical care, with oncology leading the way. One test, from Myriad Genetics, looks for mutations linked to increased risk of cancer; others, such as one offered by Foundation Medicine, help doctors prescribe drugs tailored to a particular tumor (see Foundation Medicine: Personalizing Cancer Drugs).
Veracytes first test is the only one that rules out cancer. A lump, or nodule, is caused by growths of cells in the thyroid gland, which is located in the base of the neck. Most often these growths are not cancers. To figure out whether they are, doctors will first take a small needle to extract cells from the lump and then look at the cells under the microscope. And up to 30 percent of the time in U.S. clinics, that test is inconclusive. Because cancer cant be ruled out, typically the next step is to remove the thyroid. The gland normally produces important hormones that regulate metabolism and other body functions, so patients usually then have to take hormone replacement therapy for the rest of their lives.
Between 60 and 80 percent of the time, the nodule in the removed thyroid turns out to be benign. You have unnecessarily put a patient through surgery, says Kishore Lakshman, director of a community thyroid care center in Fall River, Massachusetts. This puts patients at risk for complications such as infection, and creates dependence on hormone therapy. Since 2011, Lakshman has been using Veracytes gene test to assess the risk of cancer in patients whose initial thyroid screen was inconclusive. When I found out that there was a very efficient way of knowing the benign potential of a nodule without exposing a patient to surgery, I was quick to jump on it, says Lakshman.
Veracyte analyzed gene expression levels in hundreds of patients with thyroid nodules, some cancerous, some not, and identified 142 genes that can reliably separate benign from malignant samples. Measuring every gene in the human genome, our scientific team was able to extract genomic information and interpret it with machine-learning algorithms taught to recognize patients with benign nodules, says Bonnie Anderson, CEO and cofounder of the South San Francisco-based company.
The performance of the test was evaluated and published in the New England Journal of Medicine in 2012. That trial showed that Veracytes test can reclassify a nodule from indeterminate to benign 95 percent of the time.
In addition to saving patients from unnecessary surgeries, the test could save significant health-care dollars. A health economics study by Johns Hopkins University School of Medicine researchers found that if the test were used universally in the U.S. for patients whose needle assay was inconclusive, then approximately $122 million in medical costs would be saved each year, primarily because of the significant reduction in surgeries.
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