The VA’s list of presumptive conditions for Agent Orange exposure is a fairly long one, but many Vietnam War veterans will tell you it’s far from complete, even after the PACT Act added more. It includes many types of cancers, from lymphoma, multiple myeloma, and Hodgkin’s to non-cancerous conditions like Parkinson’s Disease.
Cancer research never stops, however, and one group of researchers looking at myelodysplastic syndromes (MDS), a group of bone marrow cancers that can progress to acute leukemia, made an interesting discovery in their review of MDS patient data from the National Heart, Lung, and Blood Institute’s MDS Natural History Study: a link between MDS cancers and Agent Orange exposure.
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In the upcoming issue of the “Blood Advances” medical journal, Dr. Mikkael A. Sekeres, Chief of Hematology at Sylvester Comprehensive Cancer Center at the University of Miami Miller School of Medicine, shows that more than 54% of MDS (or related) patients showed a history of Agent Orange exposure, compared to 37% of those who were not exposed. The study was released online before the journal’s publication.
The American Society of Hematology (ASH) findings also saw that veterans exposed to Agent Orange were diagnosed at a much younger age and that 80% of veterans saw their condition worsen within two years after receiving a diagnosis. Many devolved into a more severe MDS or leukemia.
“MDS isn’t a one-hit wonder,” Dr. Sekeres said in a 2025 interview. “Patients have one genetic mutation that occurs, then another, then another. It takes decades for those mutations to develop, and with an exposure like AO, patients can acquire that first mutation at a younger age than they normally would.”
In “Blood Advances,” Sekeres’ researchers noted that in patients diagnosed with MDS, those who had been exposed to Agent Orange were more than twice as likely to show high-risk chromosome abnormalities. These changes suggest the disease will behave aggressively.
“The progression finding was surprising,” said Sekeres. “We didn’t expect that signal to be as strong as it was.”
Dr. Mikkael Sekeres – ASH 2025
Agent Orange was a powerful herbicide used by the U.S. military during the Vietnam War. It was sprayed to destroy forests and crops, denying enemy forces access to cover and food.
But the chemical contained a highly toxic dioxin (TCDD), a chemical that disrupts cellular processes. It caused severe long-term health problems, including cancers, birth defects, and other illnesses in millions of Vietnamese civilians, American and allied veterans, and their children. It remains one of the war’s most controversial legacies. Around 2.6 million U.S. troops were potentially exposed.
Finding a link between MDS and Agent Orange is potentially important to Vietnam veterans because getting the VA to recognize MDS as a presumptive condition will mean their care for the condition is automatically covered. Affected veterans can still be service-connected for MDS, but each individual must prove the direct link between the condition and herbicide exposure.
Other studies have found some evidence of a link, but not enough for the VA to determine MDS as a presumptive condition.
“We have aging veterans developing MDS who are being told by the VA that they can’t get their health care covered to the extent they need because there hasn’t been an official association made…” Sekeres said. “Veterans have been waiting a long time for someone to take this seriously. If our work can move the needle even a little, that feels incredibly meaningful.”
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