Landgren O, et al. - Researchers sought to describe World Trade Center (WTC)-exposed firefighters with a diagnosis of multiple myeloma and to conduct a screening study for monoclonal gammopathy of undetermined significance (MGUS) and light-chain MGUS. Myeloma precursor disease (MGUS and light-chain MGUS) is linked to environmental exposure to the WTC disaster site, which could be a risk factor for the development of multiple myeloma at an earlier age, particularly the light-chain subtype.

Methods

• This is a case series of multiple myeloma in firefighters diagnosed between September 11, 2001, and July 1, 2017, together with a seroprevalence study of MGUS in serum samples collected from Fire Department of the City of New York (FDNY) firefighters between December 2013 and October 2015.
• All WTC-exposed FDNY white, male firefighters with a confirmed physician diagnosis of multiple myeloma (n = 16) and WTC-exposed FDNY white male firefighters older than 50 years with available serum samples (n = 781) participated in this study.
• Researchers defined WTC exposure as rescue and/or recovery work at the WTC site between September 11, 2001, and July 25, 2002.
• Multiple myeloma case information and age-adjusted and age-specific prevalence rates for overall MGUS (ie, MGUS and light-chain MGUS), MGUS, and light-chain MGUS were included in main outcomes and measures.

Results

• Multiple myeloma was diagnosed in 16 WTC-exposed white male firefighters after September 11, 2001; median age at diagnosis was 57 years (interquartile range, 50-68 years).
• Fourteen cases had available serum/urine monoclonal protein isotype/free light-chain data; 7 (50%) of these showed light-chain multiple myeloma.
• Myeloma cells were assessed for CD20 expression in a subset of 7 patients; 5 (71%) were CD20 positive.
• Researchers assayed peripheral blood from 781 WTC-exposed firefighters in the screening study.
• The age-standardized prevalence rate of MGUS and light-chain MGUS combined was 7.63 per 100 persons (95% CI, 5.45-9.81), 1.8-fold higher than rates from the Olmsted County, Minnesota, white male reference population (relative rate, 1.76; 95% CI, 1.34-2.29).
• Compared to the same reference population, the age-standardized prevalence rate of light-chain MGUS was more than 3-fold higher (relative rate, 3.13; 95% CI, 1.99-4.93).