Currently, only few drugs are used as cancer preventive therapy (chemoprevention), i.e. tamoxifen and raloxifene (anti-estrogens) are used in prevention of breast cancer in pre- and postmenopausal women at high risk of developing breast cancer, and sulindac and celecoxib (non-aspirin non-steroidal anti-inflammatory drugs; NSAIDs) are used in prevention of colorectal cancer in patients with hereditary colorectal cancer syndromes.

Several drugs are being evaluated as potential chemopreventive drugs, including aspirin, aromatase inhibitors, statins, and metformin. There is consistent evidence that aspirin and NSAIDs protect against colorectal cancer and that aromatase inhibitors protect against breast cancer. Self-medication, however, is strongly discouraged, and any chemoprevention with drugs should only be started after first consulting a physician who can evaluate whether treatment is appropriate and supervise the treatment.