Background Immunoglobulin E (IgE) is produced by plasma cells, often as part of an allergic immune response. It is currently unknown whether plasma IgE levels are associated with risk of cancer in individuals from the general population. We tested the hypothesis that high levels of plasma total IgE are associated with overall risk of cancer and with risk of specific cancers.

Materials and methods Plasma total IgE was measured in 37 747 individuals from the general population, and the participants were followed prospectively for up to 30 years. All statistical tests were two-sided.

Results During a mean follow-up of 7 years, a first cancer was diagnosed in 3454 participants. The multivariable adjusted hazard ratio for a 10-fold higher level of IgE was 1.05 [95% confidence interval (CI) 1.00–1.11; P = 0.04] for any cancer, 0.44 (0.30–0.64; P = 0.00002) for chronic lymphocytic leukemia (CLL), 0.53 (0.33–0.84; P = 0.007) for multiple myeloma, 1.54 (1.04–2.29; P = 0.03) for other non-Hodgkin lymphoma, 1.38 (1.04–1.84; P = 0.03) for cancer of the oral cavity and pharynx, and 1.12 (1.00–1.25; P = 0.05) for lung cancer. The findings for CLL and multiple myeloma were generally robust; however, after correcting for 27 multiple comparisons only the finding for CLL remained significant.

Conclusion High levels of plasma total IgE were associated with low risk of CLL and possibly of multiple myeloma, without convincing evidence for high risk of any cancer type.