June 8, 2011 -- Veterans of the Vietnam War may require more tailored prostate-cancer screening strategies because of Agent Orange exposure, researchers stated here at the 2011 Annual Meeting of the American Society of Clinical Oncology (ASCO).
Agent Orange, a defoliate contaminated with the known carcinogen dioxin, is a serious concern for Vietnam War veterans, and exposure may be associated with a 74% increase in risk of high-grade prostate cancer (HGPCa). The investigators found there was a unique effect on the risk of HGPCa when they looked at Agent Orange exposure, with no significant increase in risk of low-grade prostate cancer.
“Asking our patients if they had Agent Orange exposure may be the most important question you can ask,” explained investigator Mark Garzotto, MD, Oregon Health & Science University, Portland, Oregon, speaking here on June 5. “We typically ask about race and family history, but the thing that was interesting was that if they had Agent Orange exposure, then they had high-grade prostate [cancer].”
“Race and family history are not necessarily tied to grade, and we found that Agent Orange is a marker for lethal prostate cancer,” Dr. Garzotto added.
These veterans are now reaching the age at which prostate cancer is most prevalent. Recent studies suggested that Agent Orange exposure was associated with nearly a 50% increase in the risk of prostate cancer. It was unknown, however, whether Agent Orange exposure increased risks for more a more aggressive phenotype of prostate cancer.
Dr. Garzotto and colleagues examined 2,720 veterans who underwent prostate biopsy, and found that 896 (32.9%) had prostate cancer and 459 (16.9%) had HGPCa. After adjusting for significant confounders, including prostate-specific antigen density, digital rectal examination and age, men with HGPCa were more likely to have had Agent Orange exposure as compared with those with low-grade prostate cancer or no prostate cancer.
This study is one of the largest ever to examine this issue; the results, if validated, could aid in the development of effective prostate-cancer screening strategies for Vietnam-era war veterans.
“It has been a little bit controversial,” Dr. Garzotto commented in an interview with Doctor’s Guide. “Many of the studies, if not all of them, were done with relatively small numbers of patients or done with men at [an] age when they were not likely to develop it.”
[Presentation title: Agent Orange as a Risk Factor for High-Grade Prostate Cancer Detected on Initial Prostate Biopsy. Abstract 4667]