Laboratory tests showed that sulphorophane, found in broccoli and other cruciferous vegetables, can kill acute lymphoblastic leukaemia cells.
Scientists exposed leukaemia and healthy cells originating from children to a purified form of the compound.
While many of the cancer cells died, the healthy cells were unaffected, the researchers reported in the online journal Public Library of Science ONE.
Study leader Dr Daniel Lacorazza, from Bayor College of Medicine in the US, said: "Acute lymphoblastic leukaemia is a type of cancer of the white blood cells common in children.
"There's about an 80pc cure rate but some children don't respond to treatment. For those cases, we are in need of alternative treatments."