Click to Enlarge: Map showing locations of U.S. Army aerial herbicide spray missions in South Vietnam taking place from 1965 to 1971 Source: Wikipedia
WASHINGTON, DC — For the first time, new research findings have suggested that veterans exposed to Agent Orange might be at increased risk of developing progressive blood cancers, such as myeloproliferative neoplasms (MPNs).
The novel findings were presented at the American Society of Clinical Oncology 2023 annual meeting in Chicago in early June. The research was conducted at Georgetown University’s Lombardi Comprehensive Cancer Center and the Washington, DC VAMC.1
The study used a database of veterans exposed to Agent Orange, a herbicide that was used by the United States military in Korea and Vietnam to clear vegetation during combat. Agent Orange has been “associated with sarcomas and B-cell lymphomas, but not MPNs or myeloid leukemias to date,” according to a press release from Georgetown University’s Lombardi Comprehensive Cancer Center.
MPNs are “acquired stem cell disorders that can lead to overproduction of mature blood cells, complicated by an increased risk of blood clots in arteries and veins.” MPNs can become deadly leukemias when they progress, the press release added.
“We found that there is an association with Agent Orange exposure and the development of myeloproliferative neoplasms (MPNs),” lead author Andrew Chua Tiu, MD, a second-year hematology/oncology fellow with Medstar Georgetown University Hospital who conducts research at Georgetown Lombardi Comprehensive Cancer Center, told U.S. Medicine during a phone interview.
“This is the first study to demonstrate the association with myeloid malignancies,” Tiu said. “There is an increased risk of thrombosis with MPNs, including exposure to Agent Orange. We are looking into the association of increased cardiovascular risk among myeloproliferative neoplasms.”
The researchers used the VA Informatics and Computing Infrastructure (VINCI) database to examine the records of 93,269 MPN patients among more than 12 million veterans nationwide over 17 years. They explored the associations between Agent Orange and MPNs, in addition to blood clots, bleeding and a number of cardiovascular factors. Because the state of Illinois is highly representative of the U.S., based on information from the U.S. Census Bureau, the research team used veterans from the state of Illinois as a control population, according to the press release from Georgetown University’s Lombardi Comprehensive Cancer Center.
Among the significant findings, the researchers discovered the “odds of Agent Orange exposure among MPNs are 1.63 times greater than the odds of exposure among controls.”
Compared to controls, patients with MPNs had more clotting in the arteries (37% vs. 18.5%), more clotting in the veins (14.8% vs. 5.2%) and more bleeding events (39.1% vs. 13.5%). Patients with MPNs also had more hypertension (75.5% vs. 43.2%), diabetes (31.2% vs. 19%), and more heart failure (26.1% vs. 11%) than matched controls, according to the press release.
In addition, the study found the odds of Agent Orange exposure among matched controls “are 1.38 times greater than the odds of exposure among controls without arterial clots.” Also, the odds of Agent Orange exposure among MPNs with arterial clots “are 1.49 times greater than the odds of exposure among MPNs without arterial clots,” according to the press release.
Novel Findings
“These are novel findings,” Tiu said. “We are the first to demonstrate that there is an association with myeloid malignancies.”
The researchers are working on a manuscript and will submit their research findings for publication in peer-reviewed journals, Tiu added.
Tiu said he and his colleagues hope their work will help more veterans who have become ill after Agent Orange exposure become eligible for military benefits.
“Originally, the presumptive list of cancers that are associated with Agent Orange does not include any myeloid malignancies,” Tiu said. “It only included B-cell lymphomas. Hence, we explored the association of Agent Orange exposure with myeloid malignancies, and we started with myeloproliferative neoplasms, since that is my primary interest.”
“Our goal is to make MPNs part of the presumptive list so that veterans will be eligible for disability benefits,” Tiu explained.
Tiu noted that the veteran data from the VINCI database is predominantly male. Among the MPN patients, 93.6% were male, 6.4% were female, 76% white, 13.8% Black, 0.8% American Indian, 0.9% Pacific Islander and 8.5% unknown race. Also, 86.8% of patients with MPN were age 60 or older, according to the abstract from the American Society of Clinical Oncology.
“As for the difference in age, take note that those patients born before 1960 are the ones most likely exposed to Agent Orange, because that was the time when the Vietnam War and Korean War was happening,” Tiu said.
Tiu said the “findings only point to possible associations and not causes” and the researchers “will need to dive more deeply into the biology of the disease,” according to the press release.
“There are several associations between Agent Orange and health disorders that are not well understood, and we hope our work helps uncover a few of these,” Tiu said in the release.
According to the authors, significant findings from the study include:
- The odds of Agent Orange exposure among MPNs are 1.63 times greater than the odds of exposure among controls.
- When comparing patients with MPNs vs. age-, gender- and race-matched controls, there was more clotting in the arteries (37% vs. 18.5%), more clotting in the veins (14.8% vs. 5.2%) and more bleeding events (39.1% vs. 13.5%), respectively.
- Patients with MPNs had more hypertension (75.5% vs. 43.2%), diabetes (31.2% vs. 19%) and more heart failure (26.1% vs. 11%) than age-, gender- and race-matched controls, respectively.
- The odds of Agent Orange exposure among matched controls with arterial clots are 1.38 times greater than the odds of exposure among controls without arterial clots.
- The odds of Agent Orange exposure among MPNs with arterial clots are 1.49 times greater than the odds of exposure among MPNs without arterial clots.
- Tiu AC, McKinnell Z, Liu S, Diao, Association of Agent Orange and myeloproliferative neoplasms, thrombosis, and bleeding among veterans. 2023 ASCO annual meeting. June 2-6, 2023. Abstr 7011. J. Clin Oncol 41, 2023 (suppl 16; abstr 7011)
