Based on the analyzed literature focused on antioxidant enzymes and cancer, the following features can be highlighted: (i) the activity of antioxidant enzymes is important for diagnosing neoplastic diseases such as non-small-cell lung cancer, bladder cancer, ovarian cancer, and colon cancer; (ii) non-small-cell lung cancer is usually characterized by decreased SOD and CAT activity and increased glutathione GST activity. This evidence concerns the gene CAT and urinary bladder cancer.