(HealthDay News) — Health care providers are encouraged to discuss chemoprevention as a clinical option with women at increased breast cancer (BC) risk, according to a newly updated American Society of Clinical Oncology (ASCO) clinical practice guideline published online July 8 in the Journal of Clinical Oncology.

Kala Visvanathan, M.D., M.H.S., from Johns Hopkins University in Baltimore, and colleagues on ASCO’s Breast Cancer Risk Reduction Guideline Update Committee, conducted a literature review to identify randomized controlled trials and meta-analyses published from June 2007 through June 2012 with breast cancer incidence as the primary outcome of interest.

Based on 19 studies, the researchers have made the following recommendations, but caution that all discussions regarding chemopreventive agents must include mention of risks and benefits: In women 35 years of age and older at increased risk of BC, tamoxifen (20 mg per day for 5 years) may be an option to reduce the risk of estrogen receptor (ER)-positive BC; and, in postmenopausal women, raloxifene (60 mg per day for 5 years) and exemestane (25 mg per day for five years) should be discussed as options for BC risk reduction.

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Based on the National Cancer Institute BC Risk Assessment Tool or an equivalent measure, an increased BC risk is defined as individuals with a 5-year projected absolute risk of BC ≥1.66% or women diagnosed with lobular carcinoma in situ. Except for in a clinical trial, use of other selective ER modulators or other aromatase inhibitors to lower BC risk is not recommended.

“Not every woman should use these preventive agents, but we believe women who are at increased risk for breast cancer should be given the option, because in some cases the magnitude of the risk reduction is large. For some women, these therapies can reduce the risk of breast cancer by up to 50 percent,” Visvanathan said in a statement. “We now have a better understanding of the net health benefits of these interventions. This knowledge will help us identify those women in which the benefit is greater than the risk.”

Several authors disclosed financial ties to the pharmaceutical industry.