what causes myeloma

Although a tremendous amount of work has gone into the search for the cause of multiple myeloma, to date no cause for this disease has been identified. However, the search for a cause has suggested possible associations between myeloma and a decline in the immune system, genetic factors, certain occupations, certain viruses, exposure to certain chemicals including Agent Orange, and exposure to radiation.

Age is the most significant risk factor for multiple myeloma, as 96% of cases are diagnosed in people over the age of 45, and more than 75% occur in people over the age of 70. Because the peak age for multiple myeloma is among the elderly, it is thought that susceptibility may increase with the aging process and the consequent reduction in immune surveillance of evolving cancer, or that myeloma may result from a lifelong accumulation of toxic insults or antigenic challenges.

The higher incidence of myeloma in African Americans and the much less frequent occurrence in Asians suggest genetic factors.  People in agricultural occupations, petroleum workers, workers in leather industries firefighters and cosmetologists all seem to have a higher-than-average chance of developing multiple myeloma. Exposure to herbicides, insecticides, petroleum products, heavy metals, plastics, and various dusts including asbestos also appear to be risk factors for the disease. In addition, individuals exposed to large amounts of radiation, such as survivors of the atomic bomb explosions in Japan, have an increased risk for myeloma, although this accounts for a very small number of cases.

Chromosomal changes including chromosomal translocations (generally involving the Ig heavy chain gene), and chromosomal gains and losses are very frequent in myeloma. These abnormalities have an important influence on disease outcome.

It is important to remember that in most cases, individuals who develop multiple myeloma have no clear risk factors. Myeloma may be the result of several factors acting together.