OverviewThe American Cancer Society estimates that 234,190 Americans will be diagnosed with invasive breast cancer and 40,730 will die of th
The American Cancer Society estimates that 234,190 Americans will be diagnosed with invasive breast cancer and 40,730 will die of the disease in the United States in 2015.
Breast cancer is the most frequently diagnosed cancer globally and is the leading cause of cancer-related death in women.
The lifetime risk for breast cancer for women in the United States has increased from 1 in 11 in the 1970s to 1 in 8 today, a change related to shifting breast cancer risk factor demographics and the increased use of screening mammography.
Breast cancer incidence peaked around 2000 then decreased to current rates with some variation among racial and socioeconomic groups.
Between 2006 and 2010, breast cancer incidence increased slightly among African American women, decreased among Hispanic women, and was stable among whites, Asian Americans/Pacific Islanders, and American Indians/Alaska Natives.
Historically, white women have had the highest breast cancer incidence rates among women aged 40 years and older; however, incidence rates are converging among white and African American women, particularly among women aged 50 years to 59 years.
Since 1991, breast cancer mortality has been declining suggesting a benefit from the combination of early detection and more effective treatment.
The etiology of the vast majority of breast cancer cases is unknown.
However, numerous risk factors for the disease have been established.
These risk factors include: female gender; increasing patient age; family history of breast cancer at a young age; early menarche; late menopause; older age at first live childbirth; prolonged hormone replacement therapy; previous exposure to therapeutic chest wall irradiation; benign proliferative breast disease; increased mammographic breast density; and genetic mutations such as of the BRCA1/2 genes.
However, except for female gender and increasing patient age, these risk factors are associated with only a minority of breast cancers.
Women with a strong family history of breast cancer should be evaluated according to the NCCN Guidelines for Genetic/Familial High-Risk Assessment: Breast and Ovarian.
Women at increased risk for breast cancer (generally those with ≥1.7% 5-year risk for breast cancer using the Gail model of risk assessment) may consider risk reduction strategies (see NCCN Guidelines for Breast Cancer Risk Reduction).
Proliferative abnormalities of the breast are limited to the lobular and ductal epithelium.
In both the lobular and ductal epithelium, a spectrum of proliferative abnormalities may be seen, including hyperplasia, atypical hyperplasia, in situ carcinoma, and invasive carcinoma.
Approximately 85% to 90% of invasive carcinomas are ductal in origin.
The invasive ductal carcinomas include unusual variants of breast cancer, such as mucinous, adenoid cystic, and tubular carcinomas, which have especially favorable natural histories.