Breast cancer is a complex disease, resulting from the interaction of nonmodifiable factors such as an individual's genome, age at menarche, menopause, and family history; along with modifiable risk factors such as environmental, hormonal, and lifestyle factors The goal of preventing breast cancer is to identify high-risk individuals who would benefit most from preventive therapies such as chemoprevention and risk-reducing surgeries. Chemoprevention can be defined as the use of natural or synthetic chemical agents to reverse, suppress, or prevent carcinogenic progression to invasive cancer.1-5
In the United States, women who live to the age of 90 have a 1 in 8 chance of being diagnosed with breast cancer.6 In 2009, breast cancer will be the most frequently diagnosed nonskin malignancy in US women, with an estimated 192,370 cases and 40,170 deaths.7 Female breast cancer incidence rates decreased by 3.5% per year from 2001 to 2004. This decrease may reflect reduced use of hormone replacement therapy (HRT) and preventive strategies.
The Gail model8 estimates the probability that a woman who engages in annual mammographic screening will develop invasive or in situ ductal or lobular cancer over a particular age interval. The risk factors were adjusted simultaneously for the presence of the other risk factors, and only 6 factors were shown to be significant predictors of the lifetime risk of breast cancer:
Age at menarche
Number of breast biopsies (pathologic diagnosis of atypical hyperplasia)
Age at first live birth (or nulliparity)
Family history of breast cancer in first-degree relatives
The model may be accessed at www.cancer.gov/bcrisktool. The average American woman's Gail score is 0.3%, which represents her estimated risk for developing invasive breast cancer over the next 5 years; the lifetime risk for the average American woman is 10.1%. A previous diagnosis of atypical lobular or ductal hyperplasia nearly doubles the estimated risk.
The Breast Cancer Risk Assessment (BCRA) tool was updated from the results of the 2007 Women's Contraceptive and Reproductive Experiences (CARE) study in addition to the NCI's SEER program for more accurate risk assessment for African American women.9
The clinician's role in identifying candidates for chemoprophylaxis should include a detailed assessment of familial breast cancer, the opportunity for genetic testing when appropriate, comprehensive quantitative risk assessment, and a specific management prescription.10 Clinicians should also address the risks and benefits of screening, prophylactic surgery when indicated, and risk reduction using approved chemopreventive agents. In addition to genetic susceptibility, hormonally linked adult reproductive and anthropometric risk factors have been well established in the etiology of pre- and postmenopausal breast cancers.11,12 The major steps in risk assessment of breast cancer include assessment of genetic susceptibility via genetic counseling, and quantitative risk assessment via the Gail model/BCRA tool. Women at lower risk of breast cancer qualify for routine surveillance, whereas high-risk women may qualify for chemoprevention in addition to ...