Abstract
Chemoprevention is defined as the use of natural or synthetic chemical agents to reverse, suppress or prevent carcinogenic progression of invasive cancer. Drugs that act as chemoprevention agents for breast cancer are divided into two major groups: drugs that prevent Estrogen Receptor (ER)-positive breast cancers [selective estrogen receptor modulators (SERM), aromatase inhibitors GnKH agonists and phytoestrogens] and drugs that prevent ER-negative breast cancers [cyclooxygenase-2 (COX-2) inhibitors, retinoids, statins, receptor tyrosine, kinase inhibitors, monoclonal antibody against HER-2 and telomerase inhibitors]. Results from the NSABP Study of Tamoxifen and Raloxifene (STAR), which compared the risk-reducing efficacy as well as toxicity of these two SERMs in a similar high-risk for breast cancer population, showed that Raloxifene is as effective as Tamoxifen in reducing the risk of non-invasive breast cancer (p=.83). It has a statistically significant lower risk of thromboembolic events and cataracts, however a non- statistically significant higher risk of noninvasive breast cancer. Based on promising data involving reduction of contralateral breast cancer risk in adjuvant studies, several aromatase inhibitors, including letrozole, anastrozole and exemestane, are being included in trials to evaluate their efficacy in breast cancer prevention in both case-control and cohort studies As such randomized studies to confirm this efficacy are needed. Positive results of several recent clinical trials for preventing breast cancer in high-risk populations suggest that chemoprevention is a rational and attractive strategy.
Highlights
CURRENT STATUS OF BREAST CANCER CHEMOPREVENTION Chemoprevention is defined as the use of natural or synthetic chemical agents to reverse, suppress or prevent carcinogenic progression of invasive cancer
Drugs that act as chemoprevention agents for breast cancer are divided into two major groups: drugs that prevent Estrogen Receptor (ER) – positive breast cancers [selective estrogen receptor modulators (SERM), aromatase inhibitors GnKH agonists and phytoestrogens] and drugs that prevent ER - negative breast cancers [cyclooxygenase-2 (COX-2) inhibitors, retinoids, statins, receptor tyrosine, kinase inhibitors, monoclonal antibody against HER2 and telomerase inhibitors]
Results from the NSABP Study of Tamoxifen and Raloxifene (STAR), which compared the risk-reducing efficacy as well as toxicity of these two SERMs in a similar high-risk for breast cancer population, showed that Raloxifene is as effective as Tamoxifen in reducing the risk of non-invasive breast cancer (p=.83)
Summary
VILMAR MARQUES DE OLIVEIRA*, JOSÉ MENDES ALDRIGHI, JOSÉ FRANCISCO RINALDI Trabalho realizado no Departamento de Obstetrícia e Ginecologia da Faculdade de Ciências Médicas da Santa Casa de SP e Departamento de Saúde Materno-Infantil da Faculdade de Saúde Pública da USP, São Paulo, SP. Entre esses se destacam os moduladores seletivos de receptor de estrogênio (SERM), os inibidores da aromatase, os fitoestrogênios e os agonistas de GnRH na prevenção dos tumores mamários receptor de estrogênio (RE) positivos; e os inibidores da ciclooxigenase-2 (COX-2), retinóides, estatinas, inibidores do receptor de tirosina quinase (gefitinibe), anticorpo monoclonal contra HER-2 (trastuzumab) e os inibidores da telomerase, nos tumores RE negativos[7]. Estes achados foram ratificados pelos resultados do estudo NSABP B-1410, em que se observou redução de 37% na incidência de câncer de mama na mama contralateral em usuárias de tamoxifeno por cinco anos, após dez anos de estudo. Figura 2 – Risco relativo para os fenômenos tromboembólicos nos diversos estudos e na metanálise conduzida por Cuzick et al, 2003
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