Cancer chemoprevention is defined as the use of natural, synthetic, or biological chemical agents to reverse, suppress, or prevent either the initial phase of carcinogenesis or the progression of neoplastic cells to cancer.
There are three strategies for cancer chemoprevention:
1) Primary chemoprevention involves interventions designed to help healthy individuals prevent the development of a certain cancer. These individuals may have high-risk features (e.g., genetic mutations) predisposing them to cancer development.
2) Secondary chemoprevention is designed to provide treatment of premalignant lesions (e.g., colon adenomas) with the aim of preventing progression to cancer.
3) Tertiary chemoprevention aims to help patients with a history of treated cancer to prevent the development of a second primary cancer.
Vaccines targeting infections with hepatitis B virus (a risk factor for hepatocellular cancer) and human papillomavirus (a risk factor for cervical cancer) are considered cancer chemoprevention successes.
Molecularly targeted agents can prevent
• breast cancer (raloxifene and tamoxifen)
• colorectal adenomas (celecoxib)
• prostate cancer (finasteride)
Other agents that have been studied include: vitamins A, D, and E; selenium; lycopene; and NSAIDs, such as acetylsalicylic acid and indomethacin.
See reference for details. Bonovas S, Tsantes A, Drosos T, Sitaras NM. Cancer chemoprevention: a summary of the current evidence. Anticancer Res. 2008 May-Jun;28(3B):1857-66.