ROCKLAND – Military veterans exposed in Vietnam to the chemical defoliant Agent Orange have a significantly elevated risk of developing an especially aggressive form of prostate cancer, according to a new study led by a Rockland physician and researcher.

Dr. Lars Ellison, who is deployed with the U.S. Army in Iraq, said in a recent interview the research was inspired by the large number of cases of prostate cancer he and other doctors were seeing at a Department of Veterans Affairs hospital in Davis, Calif., where he practiced from 2003 to 2007.

“We noticed that a lot of veterans from Vietnam were being diagnosed with more aggressive disease,” he said. The cancers were also fast-moving, and many were not diagnosed until they already had spread to the bone or lymphatic system.

To verify and measure their observations, Ellison and professional colleagues at the University of California at Davis Medical Center used the VA’s electronic medical record system to identify about 13,000 Vietnam veterans from Northern California, half of whom had been exposed to Agent Orange during the Vietnam War and half of whom had no exposure.

Even after controlling for other risk factors – such as age, obesity, smoking, diet and medications – individuals in the group with Agent Orange exposure were twice as likely to have been diagnosed with prostate cancer, 21/2 times as likely to have an especially virulent form of the disease, and four times as likely to have metastasis at the time of diagnosis.

The implication for health care providers is clear, Ellison said. “These [veterans] are potentially harboring a much more aggressive disease than normal,” he said, and they should be managed more aggressively in response.

In addition, Ellison said, exposed veterans should make sure their doctors are aware of their high-risk status.

“They need to be very vigilant and ensure they are receiving the necessary screening tests – an annual rectal exam and a prostate-specific blood test … in order to discover any disease early.”

The study report is available online at www.ucdmc.ucdavis.edu/cancer and will be published in the Sept. 15 issue of the journal Cancer.

Routine annual screening for prostate cancer generally begins when men are 50, and includes both a physical examination and a blood test. But certain individuals, including African-American men and men with a family history of prostate cancer, are known to be at higher risk and should start screenings at age 40 instead of 50.

Ellison’s study shows that Vietnam veterans are also high-risk, but he points out they’re already past the age where early screening can be done.

“These guys are in their 50s and 60s,” Ellison said. “They’re already too old for early screening.”

Instead, the study says health care providers should be quicker to order a prostate biopsy based on the routine blood test. The test measures a protein called prostate specific antigen, or PSA. The normal range is 0 to 4 nanograms of PSA in each milliliter of blood.

At levels higher than that, and in consideration of other risk factors, doctors often will recommend a biopsy to check for abnormal cell growth. Ellison said there is some concern the 4 ng/ml threshold is too high and should be dropped to 2.5 ng/ml for the general population.

“There is now an absolutely compelling reason to lower the acceptable threshold for the Agent Orange group,” which would encourage more men to have biopsies, Ellison said. His hope is that by treating aging Vietnam veterans as the high-risk group they are, more cases of aggressive prostate cancer will be caught before the disease has spread.

Ellison said the VA has expressed interest in his study, which was presented at a urology conference earlier this year. “Hopefully, they will try to replicate it on a larger scale,” he said.

It is estimated that the U.S. military sprayed more than 20 million gallons of Agent Orange and similar chemical defoliants in Vietnam between 1962 and 1971, according to the study. Exposure to Agent Orange since has been linked with several kinds of cancer, Type 2 diabetes and birth defects in veterans’ children.

The VA maintains a registry of veterans exposed to Agent Orange. Nationally, more than 458,700 individuals are registered, including more than 5,000 in Maine.

More information about Agent Orange is available at the VA’s Web site, www1.va.gov/Agentorange.

mhaskell@bangordailynews.net

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