Follow-up Studies and Clinical Significance of Chromosomal Rearrangement in Childhood Acute Lymphocytic Leukemia / 소아과

ABSTRACT

PURPOSE: Through routine screening for chromosomal defects present in patients with acute lymphocytic leukemia(ALL) by means of reverse transcription-polymerase chain reaction(RT-PCR), we aimed for earlier detection of recurrences, hence evaluating the progress of the disease after treatment, and forecasting the need for further testing. METHODS: We analyzed 30 patients who visited the Pediatrics Department of Severance Hospital, from January 2002 to July 2003, in whom pre- and post-chemotherapy(post remission induction, post consolidateion and during maintenance) bone marrow samples were available. Among them, periodic RT-PCR examinations were performed in five bcr/abl positive cases, five TEL/AML1 positive cases, and seven dupMLL positive cases to follow the changes in genetic markers. RESULTS: In patients with bcr/abl, all five cases reached complete remission in hematologic examination after induction chemotherapy, but bcr/abl RT-PCR was positive in one case after the treatment, with complete remission reached in just four patients. In the group with TEL/AML1, all five cases reached both hematologic and molecular complete remission after induction chemotherapy. In seven cases with dupMLL, hematologic complete remission was reached in all patients, except one patient who was six months old at diagnosis, who exhibited positive findings for abnormal precursor after induction chemotherapy. CONCLUSION: Earlier detection of recurrence was possible through hematologic and chromosomal anaylsis of patients during follow-up. The most essential factor to detect recurrence considered the timing of bone marrow biopsy. So the procedure must be performed at critical intervals in a patient's course of treatment. In patients with ALL, recurrences by drug-resistant cells occur primarily after one year from the initiation of treatment, so we propose that bone marrow acquisitions to detect recurrences are recommended at one year after the start of treatment, and just before the discontinuation of treatment.