Infectious and noninfectious exposures in the etiology of light chain myeloma: a case-control study

Sixty-nine subjects with light chain myeloma were interviewed in a multicenter case-control study, and their responses were compared to those of 1683 controls selected from the general population of the same geographic areas. The interview was directed at the subject's history of exposure to a variety of chemical and infectious agents. Persons with a history of a medical implant had 2.2 times the risk of other persons (95% confidence interval = 0.9-5.8), a relative risk that increased with increasing time that the implant had been present. Alkali exposure that was deemed by the subject to be unusually heavy was associated with a relative risk of light chain myeloma of 7.8 (95% confidence interval = 1.7-35.3), while similarly defined exposure to carbon monoxide increased the risk by 6.1 times (95% confidence interval = 2.0-18.2). These findings differ from those obtained in our study of the more common forms of multiple myeloma and, while the differences are plausibly due only to chance given the large number of exposures investigated, they could be an indication that light chain myeloma is an etiologically distinct entity.