The compound, luteolin, does what chemotherapy can't, and can locate the triple-negative cancer cells and stops them metastasizing, or spreading, say researchers from the University of Missouri.
Triple-negative breast cancer cells are so called because they lack three receptors that chemotherapy drugs usually locate and latch onto, and so oncologists have to use very aggressive and toxic therapies to try to combat their spread.
The researchers have found that luteolin does the job instead. In one experiment, they found that the compound stopped the triple-negative cells spreading to the lungs, and, in a second study, they blocked their spread throughout the body. The compound also kills the cancer cells.
The tests have so far been restricted to animal studies, but the researchers are hopeful they'll get the go-ahead to start tests on cancer patients within the next couple of years.
With around a hundred women in the US alone dying every day from breast cancer, they're hoping the regulators will move quickly.