NQO1 and breast cancer: Compared to normal tissue, NQO1 overexpression occurs up to 200-fold in >80% of non-small cell lung cancer (NSCLC), up to 100-fold in >80% of pancreatic cancer, up to 10-fold in 60% of prostate cancer, up to 10-fold in 60% of breast cancer, and up to 10-fold in 50% of colorectal cancer.3–6 In preclinical models, β-lap-induced cancer cell death occurs across tumours in proportion to tumour NQO1 levels.6–8 In normal tissues, induction of NQO1, a phase 2 detoxifying enzyme, occurs rarely (e.g. with substantial exposure to polyaromatic hydrocarbons) and is short-lived (<2 h).