According to a recent article published in The Lancet, molecular detection of residual cancer in the first stages of treatment may help predict the outcomes of pediatric patients with relapsed acute lymphocytic leukemia. This may ultimately lead to individualized approaches for the treatment of these patients.
Acute lymphocytic leukemia (ALL), also called acute lymphoblastic leukemia, is a cancer of the bone marrow and lymph system. The bone marrow produces early blood-forming cells, called stem cells, which grow and mature into the three blood cell types: white blood cells, which fight infection; red blood cells, which carry oxygen to the tissues; and platelets, which help the blood to clot. ALL is characterized by uncontrolled production of immature lymphocytes, or white blood cells. These immature lymphocytes never mature enough to perform their specific function of fighting infection. In addition, these rapidly dividing cells crowd out and suppress the formation of other important blood cells, such as the red blood cells, platelets and other white blood cells. ALL is an aggressive cancer and must be treated aggressively in order to achieve optimal chances for a cure.
Despite the progress in the treatment for ALL, approximately 20-30% of pediatric patients will have a recurrence of their cancer following initial therapy. Patients who experience a recurrence of ALL have a cure rate of only 30%. Treatment options for patients with recurrent ALL include high-dose therapy with stem cell transplantation, more moderate doses of standard therapies or clinical trials.
Researchers from Germany recently analyzed patient characteristics and treatment outcomes of 30 pediatric patients with relapsed ALL. Patients underwent molecular detection of cancer from bone marrow samples at detection of recurrent cancer, day 15 and day 36 following the initiation of therapy for recurrent disease. The detection of genetic abnormalities indicative of cancer (particularly involving TcR and Ig gene arrangements) was determined through a laboratory test called a polymerase chain reaction, or PCR. PCR also quantitatively detects these abnormalities.
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The amount of residual cancer determined on day 15 of treatment for recurrent ALL was not a reliable indicator of long-term survival in these patients. However, the amount of residual cancer on day 36 of treatment was a significant indicator of their long-term survival. Patients with only a small amount of cancer according to PCR on day 36 of treatment had an 86% chance of being cured following therapy for recurrent disease. Conversely, patients who had larger amounts of cancer on day 36 had a 0% cure rate following therapy for their recurrent ALL.
The researchers who conducted this retrospective analysis suggest that PCR analysis for residual cancer during the first days of therapy may help to individualize treatment for pediatric patients with recurrent ALL. Patients with larger amounts of cancer may be treated more aggressively while patients with smaller amounts of cancer may be spared from the harsh side effects of aggressive therapy while still obtaining a cure. Parents with children with recurrent ALL may wish to speak with their physician about the risks and benefits of PCR testing during the first months of treatment or participation in a clinical trial further evaluating novel therapeutic approaches. Two sources of information regarding ongoing clinical trials include comprehensive, easy-to-use listing services provided by the National Cancer Institute (cancer.gov) and www.eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients. (The Lancet, Vol 358, No 9289, pp 1239-1241, 2001)
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