The estimated annual incidence of invasive breast cancer in the United States is in the range of 200,000 per year, and the death rate, although improving, remains close to 40,000 per year in this country.

For a woman, the estimated lifetime risk of being diagnosed with breast cancer is approximately 1 in 8.

Traditional breast cancer risk factors include female gender, increasing age, prolonged cyclic estrogen exposure, and history of chest wall irradiation.

Newer recognized breast cancer risk factors include: dense breast tissue on mammography, alcohol consumption, certain histologies identified on biopsy including lobular carcinoma in situ (LCIS) and atypical hyperplasia, and combination estrogen-progesterone postmenopausal hormone replacement therapy.

Familial breast cancer syndromes account for a minority of breast cancer cases.

Pathological mutations in BRCA-1 and BRCA-2 are estimated to be present in less than a half a percent (0.5%) of the general population, but the frequency of mutations is higher in some groups such as the Ashkenazi Jewish population. Individuals with BRCA-1 or BRCA-2 mutations may have a >80% risk of developing breast cancer by age 70 years, particularly in families in which the penetrance of the gene is high.

Other familial syndromes that account for a smaller proportion of inherited breast cancer include: the Li-Fraumeni syndrome resulting from an inherited p53 mutation, Cowden syndrome, Muir-Torre syndrome, Peutz-Jeghers syndrome, and heterozygosity for the ataxiatelangiectasia gene.

Screening mammography reduces the risk of breast cancer death, particularly for women between the ages of 50 and 69.

Tissue biopsy is required for breast cancer diagnosis and may consist of fine-needle aspiration, core biopsy, or excisional biopsy.

The most common histologic types of invasive breast cancer are infiltrating ductal carcinoma and infiltrating lobular carcinoma.

Ductal carcinoma in situ (DCIS) is an early noninvasive form of breast cancer that should not have the ability to metastasize.

Lobular carcinoma in situ (LCIS) is not a true cancer associated with increased breast cancer risk; excision of LCIS does not alter subsequent cancer risk.

Breast cancer is staged using the TNM system. Stages I, II, and III are referred to as early breast cancer and stages IIIB and IIIC are locally advanced breast cancer; Stage IV is characterized by distant metastatic disease.

Standard surgical treatment for invasive breast cancer includes either mastectomy (removal of the entire breast) or excision of the tumor (lumpectomy or partial mastectomy). In addition, evaluation of axillary lymph nodes with either an axillary dissection or a sentinel lymph node biopsy (SLNB) is usually performed.

Radiation treatment to the breast, chest wall, and/or regional lymph node regions reduces risk for local recurrence.

Adjuvant systemic treatments including chemotherapy, hormonal therapy, and biologic therapy are given to reduce the risk of developing metastatic disease by eradicating occult micrometastases.

The prognosis of metastatic breast cancer is widely variable, but life expectancy is usually measured in years.

Treatment of metastatic disease is aimed at reducing cancer-related symptoms and prolonging survival.