A five-year-old study on cases of advanced thyroid cancer in California has reared its head on social media, causing some concerned Mother Lode residents to conjecture potential health demons in their environment.

Yet, Calaveras County Public Health Officer Dr. Dean Kelaita says residents shouldn’t lose sleep over the University of California, Los Angeles (UCLA), study, which found that an abnormally high percentage of those diagnosed with thyroid cancer in the combined region of Alpine, Amador and Calaveras counties were found to have an advanced stage of the disease at the time of diagnosis.

Though this tri-county region ranked the highest in the state in terms of advanced stage diagnoses at 51%, followed by Imperial, Sutter, San Francisco and Santa Barbara counties, it does not show that residents of the Mother Lode are at a higher risk of developing thyroid cancer than those in other regions of the state.

“There’s a higher proportion of patients with later or more-advanced forms of thyroid cancer, which means it’s spread outside of the thyroid gland and might have moved to the lymph nodes or bones or other parts of the body,” Kelaita said. “It doesn’t mean that there’s more thyroid cancer here.”

Analyzing roughly 27,000 people who had been diagnosed with thyroid cancer from 1999 to 2008, the study was launched by endocrine surgeon and assistant professor Dr. Avital Harari in response to “an unusually high rate of advanced thyroid cancers” statewide, in an attempt to identify “potential geographic clustering.”

However, the study states that it found no “obvious” clustering within specific regions of California, and found that nearly half of all counties analyzed showed significantly higher rates of advanced-stage thyroid cancer than the national average.

According to Kelaita, there are pitfalls with the study that make it difficult to adequately analyze its findings. Firstly, Kelaita pointed out that researchers chose to combine counties with smaller populations into groups in order to compare those regions with more populated counties.

Due to the somewhat arbitrary groupings, Kelaita said that it is not clear what the outcome would have been if, for example, Calaveras County had been combined with a different neighboring county, like Tuolumne.

Additionally, he said the study did not control for factors including an elderly population and access to health care – relevant issues, as cancer risk increases with age, and a primary cause of advanced-stage cancer is late detection.

“More late-stage cancers diagnosed here could be because the medical care system is not as robust. People who live in rural areas might not get things checked as quickly, and there could be a delay in getting things discovered,” Kelaita said. “We’re a Health Profession Shortage Area. By definition, we do not have as many health care providers in the population as many others do.”

Though the same contributing factors could apply statewide, Harari hypothesized in a 2015 UCLA news release that exposure to pesticides from farmland might increase rates of advanced thyroid cancer in Californians.

However, according to the release and Kelaita, the only known environmental risk factor for thyroid cancer is radiation exposure.

“That alone is unlikely to explain the phenomenon,” the release states.

Kelaita agrees that it is unclear if exposure to naturally occurring radon, pesticides or heavy metals exposed by mining activities could be significant risk factors in the area.

“We’re looking for (information) to answer these questions that we don’t really have any scientific data on,” he said. “People are trying to think up why, and they make up stories.”

Nonetheless, Kelaita assures Mother Lode residents that there isn’t much to worry about.

“I’m not aware that there’s an unsafe condition in the environment or an outbreak of thyroid cancer,” said Kelaita, who confirmed that he has not seen any data showing above-average rates of thyroid cancer in the region.


Dakota graduated from Bret Harte in 2013 and went to Davidson College, NC where she earned a bachelor's degree in Arab studies. After spending time studying in the Middle East and Europe, she is happy to be home, writing about the community she loves.

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