Fifty years after the US Air Force began spraying Agent Orange in Vietnam, new research shows that veterans exposed to the herbicide are more than twice as likely to develop monoclonal gammopathy of undetermined significance (MGUS), a precursor to multiple myeloma.
A team of researchers led by Ola Landgren, Chief of Memorial Sloan Kettering’s Myeloma Service, analyzed serum samples from 459 US Air Force personnel involved in aerial herbicide spray missions during the Vietnam War, as well as 459 samples from veterans who served there at the same time but were uninvolved in the spraying missions.
All of these veterans served between 1962 and 1971, when the US military dropped more than 19 million gallons of herbicides in Southeast Asia during Operation Ranch Hand.
Researchers tested for the presence of MGUS and also concentrations of TCDD, a contaminant of Agent Orange that’s been classified as a human carcinogen since 1997.
They found 7.1 percent of Ranch Hand veterans had MGUS, a precursor of multiple myeloma, compared with only 3.1 percent of the comparison group, says Dr. Landgren — a more than twofold higher risk. The risk of getting MGUS was significantly higher among veterans younger than 70 years of age.
The researchers also found that those vets who developed MGUS had higher TCDD levels in their blood samples.
“This provides the first direct scientific evidence that there is a link between Agent Orange and the development of multiple myeloma [in Ranch Hand participants],” Dr. Landgren explains.
The findings were published in JAMA Oncology on September 3.
Wide Use and ExposureAgent Orange was the most widely used herbicide combination sprayed during the Vietnam War, according to a 2003 Department of Veterans Affairs report. Most adverse events linked to it are blamed on TCDD.
The herbicide was used to protect US troops on the ground by stripping the forests, thereby depriving enemy soldiers of protective foliage. Agent Orange was first used in 1965, according to a 2003 Department of Veterans Affairs report. More than 11 million gallons of the chemical were used as tactical herbicides.
Dr. Landgren advises Vietnam veterans to get a simple blood test to identify MGUS. Research shows that early detection of MGUS results in better outcomes for those who do develop multiple myeloma.