Review 214
IntroductionChemoprevention is defined as the use of pharmacological or natural agents that inhibit the development of a disease. In the case of breast cancer, the main chemopreventive agents used are selective estrogen receptor blockers (SERMs) and aromatase inhibitors (AIs) (1, 2). Cyclooxygenase 2 (COX-2) inhibitors, non-steroidal antiinflammatory drugs (NSAIDs), metformin, and statins are drugs that have long been in clinical use. NSAIDs are used as anti-inflammatories, analgesics, and, in the case of aspirin, antithrombotics (3); metformin is used as an anti-hyperglycemic (4) and in the treatment of metabolic syndrome (5) and polycystic ovarian syndrome (PCOS); and statins are used for the primary and secondary prevention of cardiovascular disease by lowering cholesterol levels (6). Therefore, the safety profiles and adverse reaction profiles of these drugs are well understood. Thus, these drugs are good clinical candidates for further exploration of their mechanisms of action as applied to chemoprevention of breast cancer (7-9). Current studies regarding the novel application of these drugs have been critically analyzed with respect to their potential use in breast cancer chemoprevention. However, more research is needed to prove that these studies were adequately powered and thus are of good statistical significance, so that the use of these drugs can be considered as an option for chemoprevention of breast cancer in clinical practice.
Search strategyThe papers used as references in this review were identified using relevant keywords in related search engines such as Pubmed and Google Scholar, after performing a broader search regarding the chemoprevention of breast cancer and finding mentions of these drugs in other documents. The search terms used to identify these sources include "breast neoplasms," "breast cancer," "NSAIDs," "aspirin," "COX-2 inhibitors," "COX2 inhibitors," "cyclooxygenase 2 inhibitors," "metformin," "statins," and "HMG-CoA reductase inhibitors." The search results were then filtered, analyzed, and used as references in compiling this review.
Non-steroidal anti-inflammatory drugs (NSAIDs)Various epidemiological studies have been conducted to establish a relationship between the use of NSAIDs and the incidence of breast cancer (10-12). The results of these studies are inconsistent; however, this inconsistency is most likely due to the fact that tumors have variable molecular properties (13). All NSAIDs, such as aspirin and ibuprofen, inhibit both cyclooxygenase enzymes, largely with little or no selectivity for either enzyme. Aspirin irreversibly inhibits cyclooxygenase, while ibuprofen and other NSAIDs are reversible inhibitors. A meta-analysis has been conducted, focusing mainly on the effects of aspirin and ibuprofen (14). This meta-analysis included 16 case-control studies, 18 cohort studies, 3 caseRecent evidence shows that commonly prescribed drugs, such as non-steroidal anti-inflammatory drugs (NSAIDs), metformin, and statins, may have beneficial roles in the primary ...