By Corinna Wu
The HIV–Lymphoma Nexus
By Corinna Wu
HIV, the virus that causes AIDS, wreaks havoc by attacking the body’s immune system. And one unfortunate result of those weakened defenses is that AIDS patients have 100 to 300 times greater risk of developing non-Hodgkin lymphoma than the general population. In 1992, HIV was responsible for 8 percent to 27 percent of all new lymphoma cases, according to an estimate by researchers at the National Cancer Institute. In fact, a diagnosis of lymphoma is one of the signs that an HIV infection might be present.
HIV-infected people are most likely to develop aggressive non-Hodgkin lymphomas, such as diffuse large B-cell lymphoma and Burkitt lymphoma, says hematologist-oncologist Lawrence Kaplan of the University of California, San Francisco Medical Center. The Epstein-Barr virus seems to play an important role in triggering the cancer.
An immune system compromised by HIV can’t fight off infection by Epstein-Barr, which infects B-cells. In an AIDS patient with lymphoma, the immune system is impaired, Kaplan says. “For one reason or another, you can’t control the [abnormal proliferation] of B-cells.”
Some recent studies suggest that after 1995, the incidence of HIV-associated lymphoma dropped dramatically. “Effective treatment of HIV infection is directly responsible for this decline,” Kaplan says. Around that time, combination antiretroviral therapy, known as HAART, became standard for treating HIV. And some evidence suggests that HAART may also increase survival of lymphoma patients who have HIV.
Doctors can now treat HIV-infected lymphoma patients in much the same way as they treat anyone else, even using bone marrow transplants in which some of a patient’s own marrow is removed before chemotherapy and then injected back afterward. The option of transplanting donor bone marrow into HIV patients, however, remains relatively unexplored, because it would be potentially dangerous to further suppress the immune systems of already immune-compromised patients with the drugs needed to prevent graft-versus-host disease, a condition in which white blood cells in donor marrow attack a patient’s body.
