LOS ANGELES – A team of UCLA researchers found that there are several parts of California where, in a high percentage of people with thyroid cancer, the disease is already at an advanced stage by the time it is diagnosed.

The research was led by Dr. Avital Harari, a member of the UCLA Jonsson Comprehensive Cancer Center and assistant professor of surgery.

Approximately 63,000 people were diagnosed with thyroid cancer nationwide last year, and according to the National Cancer Institute, the incidence of thyroid cancer has increased across racial, ethnic and gender lines over the past several decades. When detected early, thyroid cancer is treatable and even curable. However, survival rates are much lower for people who are diagnosed at advanced stages of the disease.

The UCLA scientists examined county-by-county data from the California Cancer Registry for 27,000 people who had been diagnosed with thyroid cancer from 1999 to 2008. To ensure that they were comparing similar population sizes, the researchers grouped together some smaller counties for the analysis.

Nationally, about 29 percent of people with thyroid cancer have advanced-stage disease by the time it is diagnosed, according to data from the NCI’s surveillance, epidemiology, and end results program. Of the 47 geographical areas the UCLA researchers analyzed, 20 had significantly higher percentages than that, ranging from 33 percent (Orange County) to 51 percent (for the combination of Alpine, Amador and Calaveras counties).

Overall, in 35 percent of Californians with thyroid cancer — 6 percentage points higher than the national average — the disease has reached the regional or distant metastatic stage, meaning that it has spread beyond the thyroid to other tissues in the neck, regional lymph nodes or other parts of the body, by the time it is diagnosed.

The research team will next look into the relationship between pesticides and radon and thyroid cancer.