Breast cancer prevention with anti-estrogens: review of the current evidence and future directions

There is a potential for reducing the incidence of breast cancer by modifying or changing the reversible risk factors like dietary modifications, modifications in the sedentary life habits, etc. One of such methods which has gained popularity now is chemoprevention. Many agents have been evaluated in the chemoprevention setting in females with increased risk of breast cancers. Metformin, NSAIDS, Bisphosphonates, and statins were evaluated by various investigators with variable results. One of the agents that have been proven to be beneficial in this setting is the anti-estrogens. A major disadvantage of chemoprevention is that unlike prophylactic mastectomy it can never reduce the risk to near zero although it reduces the risk significantly. Another issue is the compliance as chemoprevention with anti-estrogens will need to be continued for 5 years while surgery is a one-time procedure. Another disadvantage is the possible side effects peculiar to each drug used which may not be a significant concern in prophylactic mastectomy group. All these factors must also be kept in mind and properly explained to the patient before starting chemoprevention using anti-estrogens. Here in this review we intend to look into the large randomized controlled trials to quantify the present status of chemoprevention with anti-estrogens.