Agent Orange Exposure Associated with MPNs in Veterans

Exposure to agent orange is associated with an increased risk of myeloproliferative neoplasms (MPNs), increased risk of arterial thrombosis (AT), and increased bleeding, according to new research presented at the 2023 American Society of Clinical Oncology (ASCO) Annual Meeting.

MPNs, including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF), are acquired stem cell disorders. They arise from mutations and lead to thrombotic and bleeding complications. Agent orange, a chemical herbicide used during the Vietnam War, has been associated with other cancers. Researchers, led by Andrew Chua Tiu, MD, of the Georgetown Lombardi Comprehensive Cancer Center in Washington, DC, sought to understand any links between the chemical and MPNs, as well as increased risks for bleeding, AT, and venous thromboembolism (VT) in patients with MPNs.

This case-control study searched the Veterans Affairs Informatics and Computing Infrastructure database, covering the time period from January 1, 2006, to January 26, 2023. The researchers identified 95,768 patients with MPN and any bleeding events, AT, or VT. They then identified age-matched controls in the database. The MPN group was mostly male (93.6%), White (76%), and aged 60 years or older (86.8%).

Analyses showed that patients with MPNs had increased risk of AT (29.5% vs 24.5%), VT (6.7% vs 3.8%), and concomitant AT and VT (8.1% vs 4.2%). Bleeding events were more common in patients with ET, PMF, and PV versus controls. Gastrointestinal bleeding was the most common, followed by genitourinary or pulmonary bleeding. The researchers found a significant association between exposure to agent orange and the development of MPNs. Exposure also was associated with more AT in both groups, those with MPNs and those without.

“This is the largest database evaluating MPNs, thrombosis, and bleeding in veterans exposed to agent orange,” the authors wrote, adding, “Further studies, including JAK2 mutation, CHIPs, and cardiovascular risk factors, will be needed to evaluate contribution to thrombosis and bleeding risk.”

Reference

Tiu AC, McKinnell Z, Liu S, et al. Association of Agent Orange and myeloproliferative neoplasms, thrombosis, and bleeding among veterans. Abstract #7011. Presented at the 2023 American Society of Clinical Oncology Annual Meeting; June 2-6, 2023; Chicago, Illinois.