Some families seem to get more of a certain type of cancer. This could mean the family’s genes have a mutation that leads to the cancer. But how do researchers know whether the risk comes from genes or from the family’s environment? And if a genetic risk exists, how far through the family does it go? In other words, if your grandmother had thyroid cancer, are you at increased risk?

Researchers at Huntsman Cancer Institute (HCI) and the University of Utah set out to answer that question regarding a certain type of thyroid cancer. Papillary thyroid carcinoma occurs in the thyroid, a gland in the throat that makes hormones to help regulate heart rate, blood pressure, body temperature, weight, and calcium levels.

Gretchen Oakley, MD, principal investigator of the study, says patients with papillary thyroid cancer often report family members having the same diagnosis—and those patients want to know what the risk is to other relatives.

“We have never been able to fully explain how far that risk extends because we frankly just didn't know,” says Oakley. “We saw the possibility of learning the full answer to this question through the use of the Utah Population Database (UPDB).” 

Housed at HCI, the UPDB is a comprehensive population-based collection of genealogies (family trees) that are linked to statewide records in the Utah Cancer Registry and to other medical records. The UPDB is the largest, and one of the only, such databases in the world. Oakley and her research colleagues—Karen Curtin, PhD; Richard Pimentel, MSCS; Luke Buchmann, MD; and Jason Hunt, MD—used the UPDB to study 4,460 patients diagnosed with papillary thyroid cancer between 1966 and 2011 and their first- through fifth-degree relatives and spouses.

The study revealed an increased risk to first- through third-degree relatives of papillary thyroid cancer patients (see chart for an explanation of degree in relatives). First-degree relatives were more than five times more likely to be diagnosed with the cancer. Second- and third-degree relatives had a risk twice as high. Siblings of patients with the cancer were at highest risk, with almost seven times the risk. Study findings were published in the Journal of the American Medical Association: Otolaryngology Head and Neck Surgery.

pedigree chart

“The results for first-degree relatives were similar to other studies,” says Hunt, an HCI investigator and associate professor of surgery and adjunct associate professor of neurosurgery at the University of Utah School of Medicine. “What was different about this study was we were able to discover an increased risk in more distantly related relatives. And that could only be done using a database like the UPDB, with genealogies linked to cancer records.”

Curtin, associate director of the UPDB, research assistant professor in the University of Utah School of Medicine, and HCI investigator, says finding papillary thyroid cancer among more distant relations suggests a genetic cause.

“First-degree relatives, particularly siblings, likely grow up in the same household. So it’s not surprising you might see a correlation with thyroid cancer in some families exposed to the same environment. But when you find evidence of increased risk in more distant relatives [such as cousins], those relatives are less likely to share environment and more likely to share genes.”

The researchers say these results can lead to earlier detection of papillary thyroid cancer and better treatment outcomes. Further studies need to be done to determine screening recommendations for relatives at increased risk for papillary thyroid cancer and to better define the genetic predisposition to the disease.

Learn more about thyroid cancer, including risk factors, symptoms, and treatments. Or visit our Head and Neck Cancer Program webpages.