Am Fam Physician. 2010;81(6):799-800
Guideline source: American Society of Clinical Oncology
Literature search described? Yes
Evidence rating system used? No
Published source: Journal of Clinical Oncology, July 1, 2009
Available at: http://jco.ascopubs.org/cgi/content/full/27/19/3235
In 2002, the American Society of Clinical Oncology (ASCO) updated its 1999 guideline on the use of chemopreventive agents to reduce the risk of breast cancer. This guideline is an update of the 2002 guideline. Randomized controlled trials published since 2002 were identified by a literature search and reviewed by an expert panel. A consensus guideline was then developed, and addresses the following: (1) the use of tamoxifen, raloxifene (Evista), aromatase inhibitors, and fenretinide (not available in the United States) versus no pharmacologic intervention to reduce the risk of breast cancer; (2) the comparative effectiveness of tamoxifen, raloxifene, aromatase inhibitors, and fenretinide; and (3) effective and responsible communication between physicians and patients about breast cancer risk reduction in women eligible to consider use of these agents. Table 1 summarizes the updated 2009 recommendations.
| Agent | Recommendation | Dosage |
|---|---|---|
| Tamoxifen | May be offered to reduce the risk of estrogen receptor–positive invasive breast cancer in premenopausal or postmenopausal women with a 5-year projected breast cancer risk ≥ 1.66 percent* or with lobular carcinoma in situ; risk reduction benefit continues for at least 10 years; impact on breast cancer–related mortality is unknown | 20 mg per day for 5 years |
| Not recommended for use in women with a history of deep venous thrombosis, pulmonary embolism, stroke, or transient ischemic attack | ||
| Combined use of tamoxifen for breast cancer prevention and hormone therapy currently not recommended | ||
| Follow-up should include baseline gynecologic examination before initiation of treatment and annually thereafter, with timely workup of abnormal vaginal bleeding | ||
| Risks and benefits should be given careful consideration during the decision-making process | ||
| Raloxifene (Evista) | May be offered to reduce the risk of estrogen receptor–positive invasive breast cancer in postmenopausal women with a 5-year projected breast cancer risk = 1.66 percent* or with lobular carcinoma in situ; impact on breast cancer–related mortality is unknown | 60 mg per day for 5 years |
| May be used longer than 5 years in women with osteoporosis in whom breast cancer risk reduction is a secondary benefit | ||
| Should not be used for breast cancer risk reduction in premenopausal women | ||
| Not recommended for use in women with a history of deep venous thrombosis, pulmonary embolism, stroke, or transient ischemic attack | ||
| Risks and benefits should be given careful consideration during the decision-making process | ||
| Aromatase inhibitors or fenretinide† | Not recommended for use outside of the clinical trial setting to lower breast cancer risk | NA |
Recommendations
TAMOXIFEN
Women with an increased risk of breast cancer, including those with a five-year projected breast cancer risk of at least 1.66 percent (according to the National Cancer Institute Breast Cancer Risk Assessment Tool) and those with lobular carcinoma in situ, can take tamoxifen in a dosage of 20 mg per day for five years to reduce the risk of estrogen receptor–positive invasive breast cancer for up to 10 years. The benefit past five years of treatment is unknown.
The greatest benefit and fewest adverse effects were seen in premenopausal women 35 to 50 years of age who were unlikely to have thromboembolic sequelae or uterine cancer; women without a uterus; and women at high risk of breast cancer. Vasomotor and vascular adverse effects declined after treatment. Tamoxifen should not be used in women with a history of deep venous thrombosis (DVT), pulmonary embolism, stroke, or transient ischemic attack. Use of tamoxifen with hormone therapy is not recommended. Follow-up should include gynecologic examination before starting treatment, and then once per year, with a workup for abnormal vaginal bleeding. The risks and benefits of treatment with tamoxifen should be carefully considered. The impact on breast cancer–related mortality is unknown.
RALOXIFENE
In postmenopausal women with an increased risk of breast cancer, raloxifene in a dosage of 60 mg per day for five years is another option to reduce the risk of estrogen receptor–positive invasive breast cancer. Raloxifene has been shown to be as effective as tamoxifen for reducing breast cancer risk in postmenopausal women, but it was not as effective for reducing the incidence of noninvasive breast cancer. Raloxifene has a better adverse effect profile than tamoxifen, including a lower risk of thromboembolic disease, benign uterine problems, and cataracts. Raloxifene can be used longer than five years in women with osteoporosis who could also benefit from breast cancer risk reduction. It is not recommended for use in premenopausal women or those with a history of DVT, pulmonary embolism, stroke, or transient ischemic attack. The risks and benefits of treatment with raloxifene should be carefully considered. The impact on breast cancer–related mortality is unknown.
AROMATASE INHIBITORS AND RETINOIDS
The ASCO does not recommend the use of aromatase inhibitors or retinoids in reducing the risk of breast cancer outside of clinical trials.
Risk Assessment and Communication
All women at risk of breast cancer should be informed about the option to take preventive agents; therefore, risk assessment and communication should be an important part of clinical practice. Risk assessment helps to identify women who are at increased risk of breast cancer and who are more likely to benefit from risk reduction options. Women should be given a risk estimate, the anticipated benefits and risks of their risk reduction options, and any uncertainties regarding risk prediction. The greater the woman's risk of developing breast cancer, or the lower the risk of her having adverse effects from chemoprophylaxis, the more favorable her risk/benefit ratio from chemoprevention is likely to be. Because the risk of breast cancer increases throughout a lifetime, risk assessment should be done periodically.
Risk reduction strategies, including risks and benefits, should be addressed, as well as the possible impact of each chemopreventive agent on the incidence of breast cancer. During these discussions, physicians should be sensitive to the patient's needs and values. The manner in which risk information is presented can affect how the patient interprets the information. Physicians can provide this information verbally, numerically, or visually, and should provide patients with the risks and benefits in absolute and relative terms to help avoid emphasizing the benefits or harms of treatment options.
