A history of Agent Orange exposure was associated with a 75% increase in the risk for life-threatening high-grade prostate cancer, according to a cohort analysis of US veterans.
However, exposure to the herbicide did not increase the risk for low-grade prostate cancer.
Prior studies have suggested an association between exposures to Agent Orange — a commercially manufactured defoliate sprayed extensively during the Vietnam War — and the incidence of soft tissue sarcoma, Hodgkin’s disease and non-Hodgkin’s lymphoma among veterans. There also is limited evidence for possible Agent Orange association with the development of respiratory cancer, multiple myeloma and prostate cancer.
Researchers conducted the current study to evaluate the risk for prostate cancer and high-grade prostate cancer among veterans with Agent Orange exposure. They also hoped to assess whether exposure is associated with a unique increase in high-grade prostate cancer or has an identical effect on low-grade prostate cancer risk.
The analysis included 2,720 veterans who underwent initial prostate biopsy.
Veterans were classified as either ‘‘exposed’’ or ‘‘unexposed’’ in accordance with the local Veterans Affairs Medical Center standards for documenting Agent Orange exposure. Those who did not have available exposure status were classified as unexposed. Only nine (0.3%) veterans did not have clearly declared exposure status.
Prostate cancer risk in those with Agent Orange exposure was 52% greater (adjusted OR=1.52; 95% CI, 1.07-2.13) than the prostate cancer risk in those without Agent Orange exposure, according to study results.
Veterans with Agent Orange exposure exhibited a 74% greater risk for high-grade prostate cancer compared with those who were not exposed to Agent Orange (adjusted OR=1.74; 95% CI, 1.14-2.63). However, Agent Orange exposure was not found to contribute to the risk for low-grade prostate cancer (adjusted OR=1.24; 95% CI, 0.81-1.91).
In addition, Agent Orange exposure was linked to a 2.1-fold increase (95% CI, 1.22-3.62) in the risk of detecting prostate cancer with a Gleason score ≥8.
“Biomarkers for the prediction of life-threatening disease are needed to improve current [prostate cancer] screening strategies,” the researchers wrote. “In our study, a history of [Agent Orange exposure] was associated with a 75% increase in the risk of life-threatening [prostate cancer], but it was not associated significantly with an increase in [low-grade prostate cancer]. Incorporating [Agent Orange exposure] history into decision-making for [prostate cancer] screening among veterans may help to better predict clinically significant [prostate cancer] while not adding to the number of clinically insignificant [prostate cancer] diagnoses.”
Disclosure: The researchers reported no relevant financial disclosures.