Prevention of breast cancer in women who carry BRCA1 or BRCA2 mutations: a critical review of the literature.

The purpose of our study was to review the evidence for the efficacy of surveillance for early detection, bilateral prophylactic mastectomy, prophylactic oophorectomy and chemoprevention in preventing breast cancer and improving survival of BRCA1 or BRCA2 carriers. A critical review of journal articles published between 1998 and 2004 identified by searches of MEDLINE, PubMed and references of retrieved articles was undertaken. None of the current evidence is based on randomized studies. The efficacy of surveillance for early detection of breast cancer among BRCA1 or BRCA2 carriers is not yet established. Screening with clinical breast examination and mammography showed lower sensitivity in BRCA1 or BRCA2 carriers than in the general population. Screening with MRI might offer higher sensitivity rates than mammography. Prophylactic mastectomy was shown to significantly reduce the risk of breast cancer by 89.5-100%. However, of all strategies reviewed, mastectomy was the least acceptable to women at high risk. Tamoxifen use was associated with breast cancer prevention among BRCA2 carriers (RR=0.38, 95%CI: 0.06-1.56). In BRCA1 or BRCA2 carriers with breast cancer, tamoxifen use was associated with the prevention of secondary breast cancer (OR= 0.50, 95% CI: 0.28-0.89). Prophylactic oophorectomy was associated with hazard ratios for breast cancer of 0.47 (95%CI:0.29-0.77) and 0.32 (95%CI: 0.08-1.20), in retrospective and short follow-up prospective cohort studies, respectively. There is a pressing need for more studies in order to determine which of the 4 strategies alone, or in combination, is the most effective for the prevention of breast cancer and for the improvement of survival of BRCA mutation carriers.