The finding should enable doctors to identify patients with severe ALL for additional or experimental therapies when such therapies become available. The study was published in the April issue of the journal Leukemia.
"Overall, we found that many chromosome abnormalities in our group of patients made no difference at all, although particular abnormalities could," says Dr. Nyla A. Heerema, a researcher with The Ohio State University Comprehensive Cancer Center Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, and first author on the study.
"The results surprised us," she says. "We expected that additional chromosome abnormalities would mean a worse outcome."
The retrospective study involved 249 children diagnosed with ALL between 1986 and 1996 by 10 medical centers in the United States and five other countries. The children had received intensive chemotherapy and their disease had gone into complete remission.
All the children had cancers showing the Philadelphia chromosome, an alteration in the genes that indicates a poorer response to treatment. Sixty-one percent of the patients (153), showed secondary chromosome abnormalities; that is, abnormalities present in addition to the Philadelphia chromosome.
Heerema and her colleagues wanted to learn if secondary chromosome abnormalities contributed to a poor prognosis in children with ALL. They found that having most secondary chromosome abnormalities had little affect on a child's prognosis. It did, however, when they involved the loss of chromosome 7, or the part of it known as 7p, or the loss of a part of chromosome 9 known as 9p.