Radiation exposure linked to aggressive thyroid cancers — University of California San Francisco

International Team Studied Children and Teens Exposed After Chernobyl

For the first time, researchers have found that exposure to radioactive iodine is associated with more aggressive forms of thyroid cancer, according to a careful study of nearly 12,000 people in Belarus who were exposed when they were children or adolescents to fallout from the 1986 Chernobyl nuclear power plant accident.

Researchers examined thyroid cancers diagnosed up to two decades after the Chernobyl accident and found that higher thyroid radiation doses estimated from measurements taken shortly after the accident were associated with more aggressive tumor features.

“Our group has previously shown that exposures to radioactive iodine significantly increase the risk of thyroid cancer in a dose-dependent manner. The new study shows that radiation exposures are also associated with distinct clinical features that are more aggressive,” said the paper’s first author, Lydia Zablotska, MD, PhD, associate professor in the Department of Epidemiology and Biostatistics at UC San Francisco (UCSF). The paper will be published online Tuesday, Oct. 28, in the journal Cancer.

Zablotska said the findings have implications for those exposed to radioactive iodine fallout from the 2011 nuclear reactor incidents in Fukushima, Japan, after the reactors were damaged by an earthquake-induced tsunami.

“Those exposed as children or adolescents to the fallout are at highest risk and should probably be screened for thyroid cancer regularly, because these cancers are aggressive, and they can spread really fast,” Zablotska said. “Clinicians should be aware of the aggressiveness of radiation-associated tumors and closely monitor those at high risk.”

Chernobyl studies led by Zablotska also showed for the first time that exposures to the radioactive iodine after the Chernobyl nuclear plant accident are associated with a whole spectrum of thyroid diseases, from benign to malignant. Benign encapsulated tumors of the thyroid gland are called follicular adenomas, and are treated in the same way as thyroid cancer—by removing the thyroid gland, then giving patients pills to replace the hormones that are lost. Lifelong hormone supplementation treatment is both costly and complicated for patients.

Thyroid cancer is ordinarily rare among children, with less than one new case per million diagnosed each year. Among adults, about 13 new cases will be diagnosed each year for every 100,000 people, according to the Surveillance, Epidemiology and End Results (SEER) Program of the National Cancer Institute (NCI). But in the Belarus cohort, the researchers diagnosed 158 thyroid cancers among 11,664 subjects during three rounds of screening. Those who had received higher radiation doses also were more likely to have solid or diffuse variants of thyroid cancer, as well as to have more aggressive tumor features, such as spread to lymphatic vessels and several simultaneous cancer lesions in the thyroid gland. … ”

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2 thoughts on “Radiation exposure linked to aggressive thyroid cancers — University of California San Francisco

  1. “Among adults, about 13 new cases [of thyroid cancer] will be diagnosed each year for every 100,000 people, … But in the Belarus cohort, the researchers diagnosed 158 thyroid cancers among 11,664 subjects ….”

    This looks like a massive increase, about 100-fold (more than 10 times the expected number in a sample of about 1/10 the size). But to be as conservative as possible, let’s divide by 28, the number of years since the accident, because the cited rate is 13 “per year” per 100,000. That still yields about a 350% increase in frequency, coupled with a notable increase in severity, for just this one type of cancer. Given that cancers generally result in death sooner or later, I defy any nuclear cheerleader to repeat their tired talking point that “nobody has ever died as a result of a nuclear accident.” That’s a lie; the math is inescapable. You might as well say that the person you fatally stabbed 10 minutes ago isn’t really a victim since he hasn’t finished bleeding out yet.

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