Non-Hodgkin's Lymphoma: Bone Marrow Transplants

by Food and Drug Administration (FDA)

(Page 3 of 3)

NHL patients with a poor prognosis may be candidates for high-dose chemotherapy with or without radiation followed by a bone marrow transplant. The transplant is necessary to restore the blood cells killed by the intensive cancer therapy. Before therapy, a portion of the patient's bone marrow is usually extracted and may be treated in an attempt to purge any cancer cells. The bone marrow contains "stem" cells, which are immature cells from which all blood cells develop. The bone marrow is returned to the patient after therapy. Patients may also receive stem cells harvested and enriched from their blood. Growth factors to boost the production of blood cells are also used in conjunction with bone marrow transplants.

Intensive radiation or chemotherapy followed by a bone marrow transplant has a number of potential serious side effects, including life-threatening infections, bleeding, damage to the liver, kidneys, lungs or heart, and subsequent leukemia. Although FDA has approved the chemotherapy drugs and growth factors most commonly used in conjunction with bone marrow transplants for cancer therapy, it does not regulate the procedure itself, just as it does not regulate other surgery and medical procedures considered "practice of medicine."

Studies provide strong evidence that bone marrow transplants improve the long-term survival of patients with intermediate- or high-grade lymphomas that have relapsed but are still sensitive to chemotherapy. There is little, if any, evidence of patients with low-grade lymphomas benefiting from the procedure, according to NCI's Cheson. Also, bone marrow transplants are usually not effective in NHL patients whose tumors do not respond to chemotherapy. NCI is supporting more research to assess the value of bone marrow treatment for different types of NHL.

Research is also under way to evaluate the safety and effectiveness of monoclonal antibody therapies in NHL patients. Monoclonal antibodies are synthetic antibodies that latch onto specific substances called antigens. Some antigens are unique to lymphoma cells. Researchers have designed monoclonal antibodies directed towards these lymphoma antigens. The antibodies may be attached to radioactive compounds or toxins that kill cells. Monoclonal antibody therapy is designed to more selectively target cancer cells, resulting in less severe side effects than standard therapy. Researchers are also testing the anti-cancer potential of a number of compounds produced by immune cells. These compounds, which include interleukin 2 and alpha interferon, are usually given in addition to standard chemotherapy or radiation therapies.

"We're at an exciting time in lymphoma research," said Cheson. "There are a lot of promising new drugs on the horizon." And people are eyeing that horizon more intently as NHL becomes more common.

Patient Information

Patients who wish to participate in research evaluating experimental NHL treatments should contact the National Cancer Institute at (1-800) 4-CANCER.

Tracking the Cause of a Cancer Increase Medical researchers have been trying to find a reason or reasons for the rising incidence of Non-Hodgkin's lymphoma, which has been increasing in this country since the 1950s. Suspects include: pesticides, hair dyes, AIDS, immune-suppressing therapies, and improved diagnosis.

Studies on a possible relationship between pesticides and NHL were prompted by two observations. First, the central part of the United States, which is predominantly an agricultural area, has been a hot spot for NHL since 1950. Second, NHL incidence also has been increasing more rapidly in rural areas than urban areas. These findings suggest certain pesticide exposures might cause NHL in some people. The National Cancer Institute's Sheila Zahm, Sc.D., and others found a two- to eightfold increase in NHL incidence among farmers who frequently used phenoxy herbicides such as 2,4-D, which are widely used on crops such as wheat, corn, oats, rye, barley, and sugarcane. These herbicides are also commonly used to rid lawns of weeds. More research needs to be done, however, to assess the possible link between NHL and pesticides.

Researchers are also examining the potential for hair dyes to cause NHL. The largest study on this, conducted by the American Cancer Society and reported in 1994, found women who used black hair dye for 20 years or more were more than four times as likely to develop NHL than women who didn't use hair dye. This finding confirms those of other studies. But because only a small fraction of women who dye their hair use black hair dye, this alone cannot contribute significantly to the increase in NHL in recent years.

According to Carol Palackdharry, M.D., of the Medical College of Ohio, changes in diagnostic criteria can account for only about 10 to 15 percent of the current cases of NHL. A similar percentage of cases can be attributed to AIDS, researchers M.H. Gail and colleagues estimated in a 1991 issue of the Journal of the National Cancer Institute. The immune suppression AIDS induces makes people more susceptible to NHL. The increased use of immune-suppressing therapies to prevent rejection of organ transplants, and to treat rheumatoid arthritis, cancer, and other disorders might also account for a small percentage of NHL cases, according to Palackdharry.

Further research is needed to fully explain the rising incidence of NHL. As Dan Longo, M.D., formerly at NCI and now at the National Institute on Aging, sums up in the August 1994 issue of the journal Oncology, "... it appears that lymphoma incidence is a building tidal wave. What remains unclear is whether we can rapidly learn enough about the various causes to implement successful prevention strategies that will enable us to diminish the damage done by the coming wave."

About the Author

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