Breakthrough in thyroid cancer may enable more targeted risk assessment and earlier intervention

Scientists at deCODE genetics presented the discovery of two single letter variations in the sequence of the human genome (SNPs) conferring substantial increased risk of thyroid cancer.

The two SNPs, located on chromosomes 9q22 and 14q13, are the first common variants replicated in multiple populations ever associated with increased risk of the disease. They were found through the analysis of the genomes of a total of more than 40,000 patients and control subjects from Iceland, the United States and Spain. Approximately 4 percent of people of European descent carry two copies of the at-risk versions of both SNPs, putting them at a 5.7-times greater risk of thyroid cancer than individuals who carry no copies of either. These variants contribute to an estimated 57 percent of all cases of the disease, and they associate with altered levels of key thyroid hormones.

"This is an important discovery with a clear medical utility. Thyroid cancer is the most common endocrine cancer, and about 1 percent of the general population will develop it at some point in their lifetime. But if detected early enough it is in general a treatable disease. Screening for the at-risk SNPs may therefore provide a new means of identifying those who are at highest risk, enabling closer monitoring of those individuals with an emphasis on addressing other risk factors and promoting early intervention if cancer is detected. We are already including these risk variants in our deCODEme full genome scan and deCODEme Cancer scan, and are analyzing the possibility of putting them into a reference laboratory diagnostic test," said Kari Stefansson, CEO of deCODE and senior author on the study.

The paper, "Common variants on 9q22.33 and 14q13.3 predispose to thyroid cancer in European populations," is published today in the online edition of Nature Genetics, at http://www.nature.com/ng.

deCODE would like to thank all those who participated in this study, as well as the collaborating clinicians and scientists from the National- University Hospital in Reykjavik, Ohio State University and the University of Zaragoza. This project was funded in part by the US National Institutes of Health under contracts CA16058 and CA124570.