Echoes from the Past

Agent Orange Exposure Heightens Cancer Recurrence Risk

Veterans exposed to Agent Orange have a 48 percent higher risk of prostate cancer recurrence following surgery than their unexposed peers, and when the disease comes back, it seems more aggressive, researchers say.

“We need to be screening these patients earlier, treating their cancer aggressively and following them closely afterward,” said Dr. Martha Terris, chief of the Urology Department at the Augusta Veterans Affairs Medical Center and an MCG professor of urology.

“We looked at all patients, whether they were exposed or not, to see which were more likely to develop a recurrence, and patients with a history of Agent Orange exposure were more likely,” said Dr. Sagar R. Shah, an MCG urology resident who presented the data during the American Urological Association Annual Meeting in May 2007.

The study looked at 1,653 veterans who had prostate cancer surgery at Department of Veterans Affairs Medical Centers in five cities between 1990 and 2006; 199 had been exposed to Agent Orange, a herbicide and defoliant sprayed on the dense forests of Vietnam during the war.

Agent Orange contains the carcinogen, dioxin, which can be stored in body fat and is believed to penetrate the cell nucleus and work as a tumor promoter. Relatively higher mortality rates have been found in chemical plant workers and farmers with prostate cancer who were exposed to dioxin, the researchers wrote in their abstract.

Researchers found veterans with Agent Orange exposure were disproportionately AfricanAmerican and younger than average to have a cancerous prostate gland removed. (They suspect that AfricanAmericans, who were more likely to be ground troops during the Vietnam War, were at increased risk for higher levels of exposure.)

The disease appeared to be caught earlier in exposed veterans. Most had their disease staged as T1 (seemingly confined to the prostate gland) and had lower preoperative prostate specific antigen scores, an indicator of disease aggressiveness.

However, when the disease recurred, exposed veterans experienced a more rapid biochemical progression of their disease, which PSA measures. In AfricanAmericans, the PSA doubled in almost half the time of their unexposed peers.

A blood PSA level screens for prostate cancer for most men beginning at age 50 and at age 40 for blacks and men with a family history. Black men have been shown by Dr. Terris and others to have more aggressive disease earlier in life.

To account for known racial differences, researchers also compared recurrence rates in exposed and nonexposed blacks and whites. The results held up.

“As a population in general, if you were exposed to Agent Orange, you’re more likely to have a recurrence,” says Dr. Shah. “If you are black and were exposed, your cancer is more likely to recur than if you are black and unexposed.”

The study was funded by the Georgia Cancer Coalition and the Department of Veterans Affairs.

Toni Baker