Given that farnesyltransferase inhibitors (FTIs) only target HRAS effectively [19], FTIs have the potential to benefit up to 21 500 new HRAS mutated patients per year in the U.S.A. While head and neck, thyroid or bladder cancers represent obvious targets for FTI clinical trials, the estimated patient numbers make a case for wider screening, including cancers not normally thought to be associated with HRAS such as colon (∼2236 new HRAS mutant patients per year), melanoma (∼1734 patients) and breast cancer (∼1612 patients). This evidence concerns the gene HRAS and breast cancer.