In breast cancer, a more routine molecular profiling will allow the assessment of CYP expression patterns in support of patient treatment selection, e.g., tamoxifen is mostly effective in patients expressing CYP2D6 while in contrast paclitaxel is largely ineffective in patients expressing high levels of CYP2C8 and CYP3A4. The gene discussed is CYP2C8; the disease is breast carcinoma.