SAN DIEGO — Agent Orange exposure appears to be an independent risk factor for a prostate cancer (PCa) diagnosis, although it remains unclear how Vietnam veterans exposed to the defoliant fare when it comes to metastasis or mortality.
Researchers from the VA San Diego Healthcare System and the University of California San Diego in La Jolla, CA, investigated the association of Agent Orange exposure and PCa risk, using the Million Veteran Program (MVP).
The MVP, a national, population-based cohort study of U.S. military veterans conducted 2011-2021 with 590,750 male participants available for analysis. Results were reported in medRxiv as a preprint article, which means the research has not been peer-reviewed by a journal.1
The study team determined Agent Orange exposure from VA records using the official definition of Agent Orange exposure, which is active service in Vietnam while Agent Orange was in use.
“Only veterans who were on active duty (anywhere in the world) during the Vietnam War were included in this analysis,” according to the researchers, who said that 211,180 participants were involved. “Genetic risk was assessed via a previously validated polygenic hazard score calculated from genotype data. Age at diagnosis of any PCa, diagnosis of metastatic PCa and death from PCa were assessed via Cox proportional hazards models.”
Results indicated that exposure to Agent Orange was associated with increased PCa diagnosis (HR 1.04, 95% CI 1.01-1.06, p=0.003), primarily among non-Hispanic White men (HR 1.09, 95% CI 1.06- 1.12, p<0.001).
“When accounting for race/ethnicity and family history, Agent Orange exposure remained an independent risk factor for PCa diagnosis (HR 1.06, 95% CI 1.04-1.09, p<0.05),” the authors advised. “Univariable associations of Agent Orange exposure with PCa metastasis (HR 1.08, 95% CI 0.99-1.17) and PCa death (HR 1.02, 95% CI 0.84-1.22) did not reach significance on multivariable analysis. Similar results were found when accounting for polygenic hazard score.”
The article pointed out that associations with PCa metastasis or death were unclear when accounting for race/ethnicity, family history and/or polygenic risk.
- Lui AJ, Pagadala MS, Zhong AY, Lynch J, et. al. Agent Orange exposure and prostate cancer risk in the Million Veteran Program. medRxiv [Preprint]. 2023 Jun 16:2023.06.14.23291413. doi: 10.1101/2023.06.14.23291413. PMID: 37398205; PMCID: PMC10312838.