General Information About Breast Cancer

Genetic Characteristics and Risk Factors

Several well-established factors have been associated with an increased risk of breast cancer, including family history, nulliparity, early menarche, advanced age, and a personal history of breast cancer (in situ or invasive).

Age-specific risk estimates are available to help counsel and design screening strategies for women with a family history of breast cancer.[2,3] Of all women with breast cancer, 5% to 10% may have a germ-line mutation of the genes BRCA1 and BRCA2.[4] Specific mutations of BRCA1 and BRCA2 are more common in women of Jewish ancestry.[5] The estimated lifetime risk of developing breast cancer for women with BRCA1 and BRCA2mutations is 40% to 85%. Carriers with a history of breast cancer have an increased risk of contralateral disease that may be as great as 5% per year.[6] Ma le carriers of BRCA2 mutations are also at increased risk for breast cancer.[7]

Mutations in either the BRCA1 or BRCA2 gene also confer an increased risk of ovarian cancer.[7-9] In addition, mutation carriers may be at increased risk of other primary cancers.[7,9] Genetic testing is available to detect mutations in members of high-risk families.[10-14] Such individuals should first be referred for counseling.[15] (Refer to the PDQ summaries on Genetics of Breast and Ovarian Cancer; Breast Cancer Prevention; and Breast Cancer Screening for more information.)

Screening

Clinical trials have established that screening with mammography, with or without clinical breast examination, may decrease breast cancer mortality. (Refer to the PDQ summary on Breast Cancer Screening for more information.)

Patient Evaluation

Patient management following initial suspicion of breast cancer generally includes confirmation of the diagnosis, evaluation of stage of disease, and selection of therapy. At the time the tumor tissue is surgically removed, estrogen receptor (ER) and progesterone receptor (PR) status should be determined.

Prognostic and Predictive Factors

Breast cancer is commonly treated by various combinations of surgery, radiation therapy, chemotherapy, and hormone therapy. Prognosis and selection of therapy may be influenced by the following clinical and pathology features (based on conventional histology and immunohistochemistry):[16]

• The age and menopausal status of the patient.
• The stage of the disease.
• The histologic and nuclear grade of the primary tumor.
• The ER and PR status of the tumor.
• Human epidermal growth factor type 2 receptor (HER2/neu) overexpression.
• Proliferative capacity of the tumor (e.g., Ki67).

Molecular profiling has led to classification of breast cancer into the following five distinct subtypes:[17,18]

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