Scientists have pinpointed the molecular on-off switch that the powerful drug tamoxifen uses to attack breast cancer and which prevents it from working in some women.
That discovery should eventually help doctors test for resistance to the drug, the chief treatment for breast cancers that are oestrogen-driven, researchers said. Tamoxifen doesn't work in about one-quarter to one-third of women who are treated with it.
A test for resistance based on the research, published in the journal Nature, is probably about five years away, said study co-author Jason Carroll, a cancer researcher at the Cambridge Research Institute in the United Kingdom.
Tamoxifen turns off a gene that causes tumours to grow, but sometimes it fails in a molecular tug-of-war with another protein, and that's when the drug doesn't work, Carroll said. "If that switch fails, the tamoxifen fails," he said. "The switch is hidden in the background of the genome in the gene itself." – (Sapa, November 2008)