What Causes Lymphoma?

The cause of most lymphomas is not known. Most are probably caused by mutations in certain genes, called oncogenes, which then allow normal cells to divide out of control.

These factors may increase a person's risk of getting lymphoma:

• Exposure to chemicals such as certain solvents, pesticides, herbicides, and water contaminated with nitrate.

• Taking drugs that suppress the immune system.

• Having an autoimmune disease, such as lupus or rheumatoid arthritis.

• Having stomach ulcers or gastritis caused by a kind of bacteria called H. pyelori.

• Having a weakened immune system. For example, people with AIDS are 50 to100 times more likely to develop lymphoma than people who are not infected with the AIDS virus.

• Having one of the viruses that may increase risk for some types of lymphoma. For instance, in Africa, most Burkitt's lymphoma cells also carry the Epstein-Barr virus (EBV). In the United States, however, most Burkitt's lymphoma cells do not carry EBV. Viruses called HTLV-I appear to cause lymphoma in Japan, the Caribbean, and the southeastern United States. Another virus, called HHV-8, has been found in most cases of body cavity-based lymphomas (BCBL).