Children can be treated for a common form of childhood leukemia without bombarding the brain with radiation, reducing the risk that they will suffer additional tumors and thinking problems, U.S. researchers said on Wednesday.
They said chemotherapy injected into the blood and the fluid that bathes the brain and spinal cord produced results that were just as good.
"We believe children with ALL (acute lymphoblastic leukemia) do not need to get cranial irradiation preventively, which is different from what some centers recommend," Mary Relling of St. Jude Children's Research Hospital in Memphis, who worked on the study published in the New England Journal of Medicine.
Radiation was once a routine therapy for acute lymphoblastic leukemia, the most common form of childhood cancer. It is still given to 20 percent of the 3,400 youngsters in the United States who are diagnosed with ALL each year in the hopes of preventing a relapse.
But the treatment can cause second cancers, stunted growth, hormone imbalances and cognitive deficits.
In the new study, Relling and colleagues found 86 percent of the 498 children given aggressive chemotherapy survived, cancer-free, for five years.
Among 71 patients who normally would have received brain irradiation in the past, the five-year survival rate was 91 percent, much better than a comparison group consisting of children who had previously received the radiation therapy for their ALL. For them, the survival rate was 73 percent.
"These are the best results reported to date," Relling said.
The amount of chemotherapy was personalized for each child, depending in part on how many leukemia cells were detected after initial treatment.
Relling said that in the 1960s, radiation offered a big advantage in survival at a time when only 20 percent or fewer lived for five years, in part because new tumors would appear in the central nervous system. Using radiation increased the survival rate to 50 percent.
"That was a very dramatic increase in cure rates, so there was a time where almost every patient with childhood leukemia would get irradiation," she said.
"Then there was a gradual backing away from that," so only children in the highest-risk group got it, where the risk of recurrence outweighed the risk of serious side effects.
Acute lymphoblastic leukemia is a cancer of the white blood cells, the cells in the body that normally fight infections.
