January 9 (HealthDay News) -- Researchers say they have identified a rare subtype of a childhood leukemia that does not respond well to treatment.

Those with the subtype of acute lymphoblastic leukemia (ALL) have a BCR-ABL1 fusion gene. In the Dutch and German genetic analysis of children recently diagnosed with ALL, those with this gene tended to have relapse of the disease, often within five years of initially appearing disease-free.

The findings were published online Jan. 9 and will appear in the February print issue of The Lancet Oncology.

Although success rates for treating and curing many childhood leukemias are high, some with certain subtypes of ALL tend to fair poorly. About a quarter have genetically unclassified strains of the disease in which relapse is frequent.

Being able to pinpoint this disease subtype could help guide treatment decisions and improve outcomes.

"These data suggest that the BCR-ABL1-like [subtype] constitutes a large subgroup with poor prognosis that is unrecognized with current diagnostic markers," study leader Monique Den Boer, of University Medical Centre in Rotterdam, said in a news release issued by the journal. "These patients should receive more intensive therapy with available drugs or with new, more targeted drugs for which the biology of the BCR-ABL1-like subtype needs further study. Improved treatment of this high-risk leukemia will have a great effect on the overall cure rate of childhood ALL."

SOURCE: The Lancet, news release, Jan. 8, 2009