About 3 million Americans served in the armed forces in Vietnam and nearby areas during the 1960s and early 1970s, the time of the Vietnam War. During that time, the military used large amounts of mixtures known as defoliants, which are chemicals that cause the leaves to fall off plants. One of these defoliants was Agent Orange, and some troops were exposed to it. Many years later, questions remain about the lasting health effects of those exposures, including increases in cancer risk, according to the American Cancer Society.
Past studies have linked agent orange exposure to serious health issues including tumors birth defects and cancers such as breast cancer, multiple melanoma and prostate cancer however, some studies found a small excess risk of prostate cancer related to dioxin exposure until now.
A new study led by Dr. Mark Garzotto, MD, associate professor of surgery/urology at Oregon Health and Science University, Chief Urologic Oncology, Portland VA Medical Center and colleagues have found that agent orange is not linked to a small excess risk of prostate cancer but is linked to a two-fold significant risk of developing the most deadliest forms of prostate cancer.
In this cohort study researchers looked for a link between Agent Orange exposure and life-threatening, or high-grade, prostate cancer, Nathan Ansbaugh, MPH, designed and conducted analyses on a group of 2,720 US Veterans who were referred by multiple providers for initial prostate biopsy. Biopsy results and clinical information were compiled for analysis by principal investigator Dr. Garzotto.
Risk factors included family history of prostate cancer, digital rectal examination, prostate-specific antigen (PSA) density, body mass index, and service branch history. Agent Orange exposure was collected through entry in electronic health records. Those with missing data were considered unexposed.
Participants were mostly Caucasian, average age 64.7, 39.4% were overweight and 42.9% obese.
Prostate biopsy showed 896 participants had prostate cancer and that the cancer was high-grade in 459 of those cases. Medical records showed 203 participants had been exposed to Agent Orange.
Exposure was significantly tied to prostate cancer (P=0.017), and especially so for high-grade prostate cancer (P=0.01) -- a 52% and 74% increased risk, respectively. Agent Orange exposure was associated with a 2.1-fold increase (95% CI 1.22-3.62, P<0.01) in the risk of detecting prostate cancer with a Gleason score ≥8.
Independent predictors included positive family history, older age, Marine Corps service, and increased PSA density.
According to the researchers the findings from this study shows knowing whether they have been exposed to Agent Orange is a readily identifiable way to improve prostate cancer screening for Veterans. Lethal cases would be spotted earlier, which with prompt treatment could potentially prolong survival and improve quality of life for patients.
Dr. Garzotto stated “It also should raise awareness about potential harms of chemical contaminants in biologic agents used in warfare and the risks associated with waste handling and other chemical processes that generate dioxin or dioxin-related compounds.”
The authors note that their findings should influence prostate cancer screening screening practices for veterans, particularly those who have been exposed to Agent Orange.
This study is expected to be published in the journal Cancer today.
More information on Agent Orange and cancer can be found online at the American Cancer Society website.
Citation "Agent orange as a risk factor for high-grade prostate cancer" Cancer 2013
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