Breast cancer continues to occupy a prominent role in the public consciousness, and the media heighten that interest with a regular influx of new information from multiple sources, often conflicting and confusing. Breast cancer touches most health care providers in some way, whether personally or professionally; many will treat patients with the disease. With the overwhelming information available, all providers would benefit from a basic understanding of the rationale of current treatment approaches for early breast cancer, as well as of the promising new options in radiotherapy.
Incidence and prevalence
The American Cancer Society (ACS) estimates that in 2005, approximately 211,240 new cases of invasive breast cancer will be diagnosed in the United States, and 40,410 women will die from the disease.1 At 32%, 
breast cancer is the most frequently diagnosed cancer in women, and a woman's lifetime risk of developing breast cancer is now 1 in 7, whereas it was 1 in 11 in 1975.1 The risk of developing breast cancer increases with age; the majority of new cases occur in women older than 50 years. In total, 1 in 33 women will die of breast cancer; it is the second leading cause of cancer deaths in women, after lung cancer and before colon cancer.1 However, between 1990 and 2000, breast cancer mortality declined 2.3% annually, and today's 5-year survival rates for breast cancer can be higher than 97% in women with early-stage disease. Fortunately, more than 60% of women with breast cancer now receive a diagnosis of early-stage disease.1,2
Current screening guidelines for breast cancer
While ongoing technological advances in breast imaging do have an impact on breast cancer screening and follow-up recommendations in selected patients, the ACS3 and National Cancer Institute4 (NCI) currently continue to recommend the following general screening guidelines:
- Women should have routine mammography every 1 to 2 years starting at age 40 years.
- Routine clinical breast examinations should be performed as part of routine health screenings, beginning in the third decade.
- Women should know how their breasts normally feel and report any change to their health care providers. Breast self-examination is an option for women starting in their 20s.
- Women at increased risk of breast cancer should discuss with their medical provider the benefits and limitations of starting mammography screening earlier; having additional tests, such as breast ultrasonography and MRI; or having more frequent examinations.
Quantifying risk—the Breast Cancer Risk Assessment Tool
The NCI's Breast Cancer Risk Assessment Tool (BCRAT), a modified Gail Model, is a computer-based program, 
available to anyone, that calculates a woman's relative risk for the development of invasive breast cancer over a 5-year period and over her lifetime to age 90 years and compares this to same-age women of average risk. Only about 20% of diagnosed breast cancer cases can be accounted for by standard risk factors: age, age at menarche, age at first live birth, number of first-degree relatives (mother, sisters, and/or daughters) with breast cancer, number of previous breast biopsies (whatever the findings), at least one biopsy finding of atypical hyperplasia, and history of lobular carcinoma in situ (LCIS) or ductal carcinoma in situ (DCIS).
The program will underestimate the risk for a woman with a previous diagnosis of breast cancer and does not take into account inherited genetic mutations (BRCA1 or BRCA2) for breast cancer. The projections assume that the woman is receiving regular clinical breast examinations and undergoing routine screening mammography. Other risk factors, such as age at menopause, dense breast tissue on mammogram, use of oral contraceptives or hormone replacement therapy, high-fat diet, alcohol use, physical inactivity, obesity, or environmental exposures, were not included; evidence is either inconclusive or contribution to overall risk from these factors cannot be calculated. The BCRAT is available at http://bcra.nci.nih.gov/brc.