An increased risk of developing myeloma has been detected among agricultural workers in many countries. The number of cases is small, however, and more research is needed to confirm this association.
Genetic factors probably play an important role in determining who will develop myeloma. Myeloma develops frequently in some inbred strains of mice but rarely in other inbred strains. There are marked racial differences in the incidence of myeloma. The incidence is low in China and Japan and in Chinese and Japanese immigrants to California and Hawaii. The incidence of myeloma is intermediate in Caucasians in America and Europe. African-Americans have an incidence rate that is double the rate in Caucasians. In addition, there are many families in which two or more members have developed myeloma.
There is no evidence that allergies, chronic infections or other immune-stimulating conditions play a role.
