Relationship between low serum immunoglobulin E levels and malignancies in 9/11 World Trade Center responders

Background: Individuals with very low immunoglobulin E (IgE) levels have a high risk of developing malignancy. Previous studies have revealed that World Trade Center (WTC) responders exposed to carcinogens have an elevated risk of some cancers. Objective: To evaluate the association between low-serum IgE levels and cancer development in WTC-exposed responders. Methods: IgE levels were measured in 1851 WTC responders after September 11, 2001. This is the first pilot study in humans comparing the odds of developing cancer in this high-risk population, between the “low-IgE” (IgE in the lowest third percentile) vs “non–low-IgE” participants. Results: A significantly higher proportion of hematologic malignancies was found in low-IgE (4/55, 7.3%) compared with non–low-IgE (26/1796, 1.5%, P < .01) responders. The proportion of solid tumors were similar in both groups (5.5% vs 11.4%, P >. 05). After adjustment for relevant confounders (race, sex, age at blood draw, WTC arrival time, smoking status), the low-IgE participants had 7.81 times greater odds (95% confidence interval, 1.77-29.35) of developing hematologic cancer when compared with non–low-IgE participants. The hematologic cancers found in this cohort were leukemia (n = 1), multiple myeloma (n = 1), and lymphoma (n = 2). No statistical significance was found when estimating the odds ratio for solid tumors in relation to IgE levels. Conclusion: WTC responders with low serum IgE levels had the highest odds of developing hematologic malignancies. This hypothesis-generating study suggests that low serum IgE levels might be associated with the development of specific malignancies in at-risk individuals exposed to carcinogens. Larger, multicenter studies with adequate follow-up of individuals with different IgE levels are needed to better evaluate this relationship.