Clinicians should discuss the prophylactic use of tamoxifen (Nolvadex) as well as two other agents with women 35 years and older and at increased risk of estrogen receptor (ER)-positive breast cancer, according to revised recommendations from the American Society of Clinical Oncology (ASCO).

ASCO’s updated guideline, Use of Pharmacologic Interventions for Breast Cancer Risk Reduction: American Society of Clinical Oncology Clinical Practice Guideline, replaces the 2009 version. The original guideline appeared in 1999 and underwent its only revision prior to the 2009 reworking in 2002.

The latest document strongly recommends that health care providers discuss the use of tamoxifen with premenopausal women, and tamoxifen and raloxifene (Evista) with postmenopausal women, who are at increased risk for breast cancer. Exemestane (Aromasin) is another option for postmenopausal women.


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The key recommendations are:

• Premenopausal and postmenopausal women 35 years and older who are at increased risk of breast cancer, specifically ER-positive disease, or who have lobular carcinoma in situ (LCIS), should discuss with their health care provider the option of taking tamoxifen 20 mg/day orally for 5 years to reduce the risk of invasive breast cancer. Tamoxifen use is not recommended in combination with hormone therapy or during prolonged immobilization, nor is it recommended for women with a history of deep vein thrombosis, pulmonary embolus, stroke, or transient ischemic attack (TIA). This antiestrogen agent also is not recommended for women who are pregnant, who may become pregnant, or who are nursing a child.

• Raloxifene 60 mg/day orally for 5 years is also an option for reducing the risk of invasive breast cancer, specifically ER-positive breast cancer, in postmenopausal women 35 years or older who are at increased risk of breast cancer or who have LCIS. Raloxifene, a selective estrogen receptor modulator (SERM), is not recommended for women with a history of deep vein thrombosis, pulmonary embolus, stroke, or TIA, or for use during prolonged immobilization.

• Use of the aromatase inhibitor exemestane, 25 mg/day orally for 5 years, is an alternative to tamoxifen or raloxifene therapy in reducing the risk of invasive breast cancer, specifically ER-positive disease, in postmenopausal women 35 years and older who have an increased risk of breast cancer or who have LCIS or atypical hyperplasia. Exemestane should not be used to reduce breast cancer risk in premenopausal women.

• The most favorable risk-benefit profile of taking prophylactic tamoxifen or raloxifene is seen in women who are at greatest risk of developing breast cancer.

• Discussions with patients should address the risks as well as the benefits of each drug being considered.

The ASCO guideline was published online ahead of print in July 2013 by Journal of Clinical Oncology and was authored by a panel co-chaired by Kala Visvanathan, MBBS, FRACP, MHS, associate professor of epidemiology and oncology at the Johns Hopkins Bloomberg School of Public Health and the Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, both in Baltimore, Maryland. ONA