A new kind of stem cell transplant may now cure patients with a lymphoma that has been considered incurable in the past. In a report in the journal Blood (Vol. 98, No. 13: 3595-3599), researchers at M.D. Anderson Cancer Center reported that 17 of their 20 patients were cleared of all lymphoma cells.

The patients all had low-grade lymphomas. Low-grade lymphoma and chronic lymphocytic leukemia, which is like low-grade lymphoma in many ways, affect about 25,000 to 30,000 people each year in the US, according to the American Cancer Society (ACS).

Though low-grade lymphoma grows slowly, it will eventually be fatal. All the patients had responded to chemotherapy and then relapsed. They were then put into remission with new chemotherapy and given the transplant.

In a stem cell transplant, cells are separated from the blood and then transfused into the patient after he or she has received large doses of chemotherapy and sometimes radiation.

The type of transplant the patients in the study had is called nonablative or non-myeloablative. This means that they were treated with low doses of chemotherapy before the transplant. In the past, high doses of chemotherapy were used. But doctors learned that this wasn't needed in all cases.

Now, only enough chemotherapy is used to allow the stem cells to "take." As the transplanted cells take over, they develop an immune reaction against the cancer. This is called a graft versus cancer effect.

The advantage of this approach is that it is done on an outpatient basis, it is much less toxic, and can be done in older patients. In the past, only patients younger than 50 were given stem cell transplants because chemotherapy was too toxic for older patients. Two of the patients in this study were over 65.

The transplants all came from siblings that were matched to the patient. In the past, bone marrow was used as the source of stem cells. Now modern techniques allow doctors to separate stem cells from the donor's blood.

The downside of this treatment is the immune response by the graft. Although it eliminates the lymphoma cells, it also attacks the patients' tissues and organs. This is called graft versus host disease or GVHD. This can be serious, and sometimes fatal.

Patients with GVHD can develop severe diarrhea, rashes, and are susceptible to life-threatening infections. About half the patients in this study developed GVHD.

The patients were all given drugs to prevent GVHD, or at least temper its effects. These were successful enough so that most of the patients could lead normal lives. But it is a problem in transplants and is attracting a large amount of research interest. Scientists are developing ways to avoid GVHD and keep the immune reaction to the cancer.

What if a person doesn't have a sibling match? Although this study did not report on this issue, experts can point to advances in science that have made this less of a problem. The US, as well as Europe, has a large registry of donors who are willing to donate their blood for stem cell transplants. Immunologic identity is now determined through genetic testing. With this approach, donors can be found that are as close as a sibling.

Is this procedure for all patients with low-grade lymphomas? Not yet, according to the authors. The patients have only been followed for two years, and this approach needs to be tested against standard treatment.

The good news is that once the lymphoma has been eliminated, all evidence points to this being permanent, the authors said. And once the GVHD problem can be eliminated, this may be the favored treatment for patients with low-grade lymphomas.