LOS ANGELES (AP) -- Adults with a common form of leukemia had a better chance of remission if they got a double dose of a long-used cancer drug, two new studies found.

Doctors said the findings should change the standard of care for younger adults with acute myeloid leukemia, but work remains to find better treatment for the elderly, who are more likely to develop the disease.

Acute myeloid leukemia is a cancer of the blood and bone marrow. It's the most common type of acute leukemia in adults. About 12,810 new cases will be diagnosed in the United States this year, according to the Leukemia & Lymphoma Society.

Patients typically receive two chemotherapy drugs to slow or stop the growth of cancer cells in the body. Two studies published in Thursday's New England Journal of Medicine looked at how patients fared if the dose of one of the chemo drugs, daunorubicin, was doubled.

One study led by researchers at the Moffitt Cancer Center and Research Institute in Florida gave 657 leukemia patients ages 17 to 60 either the standard chemo dose or double the amount and followed them for about two years. Complete remission occurred in 71 percent of those who took the higher dose, compared with 57 percent in the regular dose group. Overall survival was also higher in those who had more chemo: 24 months versus 16 months.

The other study led by Erasmus University Medical Center in the Netherlands looked at an older population -- ages 60 to 83 and followed them for three years. Of the 813 volunteers newly diagnosed with AML, 64 percent in the double-dose group had complete remission compared with 54 percent in the standard dose group. Overall, there was no difference in survival between the two groups, except those under 65 who got the double dose did better.

In an accompanying editorial, Drs. Herve Dombret and Claude Gardin of Hospital Saint-Louis in Paris wrote that the results warrant giving younger leukemia patients a higher chemo dose. Since many elderly patients will not benefit from more chemo, doctors need to find new ways to help this age group, they said.

The American study was funded by the National Cancer Institute and Department of Health and Human Services. One of the authors received support from Wyeth Pharmaceuticals and Immunex, which make chemo drugs. The European study was supported by the Dutch Cancer Society Queen Wilhelmina Foundation.

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