Numerous human cancers, including colorectal cancer 1, lung cancer 2, breast cancer 3, cholangiocarcinoma 4, ovarian cancer 5, uterine cervical cancer 4, pancreatic cancer 4, prostate cancer 5 and head-and-neck cancer 6, express 5- to 200-fold higher levels of NQO1 than their healthy tissue counterparts. This evidence concerns the gene NQO1 and breast cancer.