The largest study to date of responders to the World Trade Center attacks in New York, NY, on 9/11 reports that exposed firefighters have roughly twice the risk of developing multiple myeloma precursor disease as the general population. Moreover, firefighters who go on to develop multiple myeloma exhibit a younger age of onset and more aggressive disease than is typical.

Following the attacks on the World Trade Center (WTC) in New York, NY, on 9/11 (September 11, 2001), thousands of first responders were exposed to carcinogens in dust and gases. Since then, researchers have wondered about the possible impact on cancer rates. Although some studies have found an elevated risk of multiple myeloma and other cancers in first responders, others have not. In the most recent and largest study to date, exposed firefighters had roughly twice the risk of developing multiple myeloma precursor disease as the general population.

Moreover, “we found earlier age of onset and more aggressive multiple myeloma among World Trade Center–exposed firefighters compared to what is seen in the general population,” says lead author Ola Landgren, MD, PhD, of Memorial Sloan Kettering Cancer Center in New York, NY. “Taken together, these observations suggest World Trade Center exposure is a risk factor for myeloma.”

Landgren says the study was triggered when physicians at his institution reported seeing aggressive cases of multiple myeloma in relatively young WTC responders. The researchers analyzed the 16 cases of multiple myeloma diagnosed among Fire Department of New York (FDNY) firefighters since 9/11. The median age at diagnosis was 57 years, roughly 12 years younger than the national average age at onset. In addition, the proportion of firefighters with CD20-expressing plasma cells, which are associated with a poorer prognosis, was roughly 3.5 times higher than has been reported in other multiple myeloma studies.

Next, the study capitalized on the FDNY's WTC Health Program, which has a bank of blood samples from the regular health screenings it provides, to look at rates of multiple myeloma precursor disease. (Because precursor disease is more common and develops more rapidly after exposure to a carcinogen than multiple myeloma, it is easier to study.) After analyzing serum samples from 781 white, male, 50- to 79-year-old WTC-exposed firefighters, they found the age-standardized prevalence for precursor disease was 7.63 per 100 people, whereas that for similar-aged men screened as part of a study in predominantly white Olmsted County, MN, was 4.34.

Although these results are striking, a consistent problem for this and other WTC studies has been identifying appropriate comparison groups, says Laurie Gold, PhD, of the University of Washington in Seattle. Here, “the comparison group may have been different from the World Trade Center responders in ways that had nothing to do with the carcinogens that the responders were exposed to after 9/11,” she says. Unfortunately, no data exist for a comparison group of firefighters with no WTC exposure.

Another potential problem is that 11,769 WTC-exposed firefighters did not provide blood samples for analysis. Gold wonders whether individuals who supplied a sample may have been more likely to suffer from precursor disease. “Were they experiencing health symptoms that they hoped to have explained?”

Despite the limitations inherent in studying this problem, Landgren hopes that these findings will convince the WTC Health Program to add multiple myeloma screening to the list of services provided to exposed firefighters, and also spur interest in developing better strategies to protect firefighters from inhaling hazardous dust and fumes. In the future, his team plans to expand their studies to other WTC-exposed individuals, including police officers and people who lived or worked in the area. –Kristin Harper