More chemo effective against leukemia

MEMPHIS, Tenn. — When an initial round of intense chemotherapy fails to subdue a child's leukemia, doctors typically try a bone-marrow transplant as a desperate backup measure to control the cancer.

But a new study involving St. Jude Children's Research Hospital in Memphis suggests that's not always the best strategy.

Instead, according to the unprecedented international study, some kids whose cancers withstand an initial “induction” therapy appear to benefit from additional chemotherapy instead of the transplants.

The study, recently published in the New England Journal of Medicine, will lead to immediate changes in the way certain subtypes of acute lymphoblastic leukemia (ALL) are treated, said Dr. Ching-Hon Pui, chairman of St. Jude's oncology department and one of the corresponding authors of the paper.

“We should not transplant them right away,” Pui said, adding that a different mix of chemotherapy drugs appears to be a better answer.

ALL is the most common type of childhood cancer, and through therapies it has pioneered, St. Jude cures about 90 percent of kids afflicted with the disease.

The initial treatment strategy in ALL cases is to zap the leukemia into remission through a grueling four-to-six-week round of chemotherapy known as induction. But in 2 percent to 3 percent of cases, the cancer persists after induction — and for these patients the outlook is grim, with only about one-third surviving 10 years.

To improve that survival rate, researchers in the study combed through data from more than 44,000 patients age 17 and younger who were diagnosed between 1985 and 2000, when the long-term survival rate for ALL had reached about 80 percent. The patients were from hundreds of institutions worldwide, including St. Jude.

Of the 1,041 patients who failed to go into remission after induction, one subset fared much better than others.

Those patients had leukemia that began in white blood cells destined to become B cells — the type accounting for 85 percent of ALL cases — and were treated with chemotherapy instead of transplants. Their 10-year survival rate was 72 percent, compared to 32 percent for all patients who failed induction.

The findings came as a surprise, Pui said. “We thought everybody would do poorly.”

However, the study found that bone-marrow transplants remain the best option for many other patients who fail induction therapy.

Dr. Paul S. Gaynon, professor of pediatrics at the University of Southern California and another of the corresponding authors, said the findings show that there is a vast array of subtypes of ALL.

“We're learning that leukemia, like other cancers, is more than just one disease,” Gaynon said.