New Key to Breast Cancer Discovered

Scientists believe they've made a breakthrough discovery in why a certain genetic mutation can cause a particularly deadly form of breast cancer. Mutations in the BRCA1 gene are apparently linked to the loss of an important protein, PTEN, that checks cell growth, according to a new study in the journal Nature.

Between 50% and 85% of women with a BRCA1 mutation will develop breast cancer, accounting for up to 10% of breast cancer cases. The so-called "triple-negative" type of cancer linked to the gene doesn't respond well to current treatments. Scientists hope this finding will lead to new treatments. (More breast cancer stories.)