| Abstract: | The purpose of this population-based case-control study was to learn whether risk factors differ for the individual immunoglobulin types of multiple myeloma. In particular, we sought to determine whether IgA and IgG myeloma were related to a history of exposure to reported IgA- and IgG-stimulating conditions, respectively, or to a history of selected occupational and physicochemical exposures. The M-component immunoglobulin type was determined from immunoelectrophoresis as reported in medical records, and exposure status was obtained through in-person interviews. IgG (56 percent) and IgA (22 percent) M-components predominated. For 17 percent of cases, no peak was found on immunoelectrophoresis; they were presumed to have light-chain myeloma. Persons with these three types of myeloma did not differ with respect to distributions of age or race, but a somewhat higher proportion of light-chain cases were women (58 percent cf 45 percent of all other cases). Detailed analysis of the IgA and IgG subtypes provided little evidence that they differ with respect to prior immune stimulation or employment in several specific jobs. IgA myeloma, but not IgG myeloma, was associated modestly with a history of exposure to chest and dental X-rays. Our study provides little evidence that IgA and IgG myeloma differ with respect to the risk factors examined.Ms Herrinton and Drs Koepsell, Weiss, and Daling are with the Department of Epidemiology, University of Washington, Seattle, WA, USA, and the Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA. Dr Demers is with the Department of Environmental Health, University of Washington, Seattle, WA, USA. Dr Taylor is with Group Health Cooperative of Puget Sound, Seattle, WA, USA. Dr Lyon is with the School of Medicine, University of Utah, Salt Lake City, UT, USA. Dr Swanson is with the Cancer Center, Michigan State University, East Lansing, MI, USA. Dr Greenberg is with the School of Public Health, Emory University, Atlanta, GA, USA. Address correspondence to Ms Lisa Herrinton, Fred Hutchinson Cancer Research Center, 1124 Columbia MP-381, Seattle, WA 98104, USA. The project was supported by grants CA23350, CA39779, and CA09168 from the US National Cancer Institute. |
