Chronic lymphocytic leukemia is, in general, an incurable cancer. Doctors have learned from studies in other leukemias that one way to cure more patients is to administer large doses of chemotherapy drugs for a short period of time. The high doses of chemotherapy destroy more cancer cells. The high doses of chemotherapy also damage the bone marrow stem cells necessary for blood cell production. Infusion of stem cells previously collected from a donor or the patient, however, can be used to support rapid recovery of the bone marrow after high-dose chemotherapy treatment. The process of collecting stem cells from a donor is referred to as allogeneic and stem cells collected from the patient is referred to as autologous.
The only potentially curative therapy for patients with chronic lymphocytic leukemia is an allogeneic stem cell transplant. Allogeneic transplants are not suitable for the majority of patients with chronic lymphocytic leukemia because the disease occurs predominantly in older patients. Unfortunately, allogeneic stem cell transplant is associated with considerable side effects in older patients.
Autologous stem cell transplants are standard treatment for many types of cancer. High-dose chemotherapy with autologous stem cell transplantation has been explored as an alternative to allogeneic transplantation for patients with chronic lymphocytic leukemia because it is associated with fewer side effects and may be more tolerated by older patients.
Physicians affiliated with the International Project on CLL/Transplants have evaluated the outcomes of 107 patients with chronic lymphocytic leukemia who were treated with high-dose chemotherapy and autologous stem cell transplant. The average age of the treated patients was 50 years (22-63). The results of their analysis were presented at the American Society of Hematology meeting in New Orleans.
The average time from diagnosis to treatment was 38 months. Patients had received an average of 2 previous treatment regimens before high-dose therapy. Patients were treated with chemotherapy before high-dose chemotherapy treatment in order to minimize the amount of cancer cells collected with the stem cells. Additionally, 59% of patients had the stem cells further treated in an attempt to remove any remaining cancer cells before reinfusion.
Ninety per cent of patients achieved a complete remission with high-dose chemotherapy treatment. Seven per cent of patients died from complications of treatment. Fifty per cent of patients developed cancer recurrence within 4 years from treatment. The average duration of survival from diagnosis was 12 years, which is longer than would have been anticipated for this group of patients.
It can probably be concluded from this study that survival of bad risk patients with chronic lymphocytic leukemia can be prolonged following treatment with high-dose chemotherapy and autologous stem cell transplant. Treatments that prevent relapse after transplant need to be developed to further improve this treatment approach and make it a generally curative treatment option. (Blood, Vol 94, No 10, Supplement 1, Abstract 1758, pp397a, 1999)
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