Breast Cancer - Basic Principles

Breast cancer is the most common type of cancer diagnosed in women, excluding skin cancer.

Breast cancer is the second leading cause of death from cancer in women.

Increased estrogen exposure is associated with breast cancer risk. Factors like early menarche and late menopause contribute.

Ductal carcinoma in situ (DCIS) is cancer confined to the milk ducts, not invading surrounding tissue.

Invasive ductal carcinoma is breast cancer that has invaded the surrounding tissue beyond the milk ducts.

HER2/neu amplification is associated with a good response to trastuzumab (Herceptin), a targeted therapy for breast cancer. This receptor is present on the cell surface and is involved in cell growth and survival.

Triple-negative breast cancers lack expression of estrogen receptor (ER), progesterone receptor (PR), and HER2/neu. They generally have a poorer prognosis and are more common in African American women.

Hereditary breast cancer accounts for about 10% of all breast cancer cases and is often associated with family history of breast cancer at an early age, multiple breast tumors in one individual, or breast cancer in male relatives.

Mutations in BRCA1 and BRCA2 genes are the most important genetic factors associated with hereditary breast cancer. BRCA1 mutations are associated with both breast and ovarian cancer, while BRCA2 mutations are linked to breast cancer in males.

Prophylactic bilateral mastectomy, the removal of both breasts, can be a preventative measure for women with a high genetic risk of developing breast cancer. However, a small risk of cancer still exists due to potential extension of breast tissue into surrounding areas.

A type of invasive ductal carcinoma characterized by well-differentiated tubules lacking myoepithelial cells. Tends to occur in older women (average age is 70 years). Has a relatively good prognosis.

A type of invasive ductal carcinoma characterized by large, high-grade cells growing in sheets with lymphocytes and plasma cells. Grows as a well-circumscribed mass that can mimic fibroadenoma on mammography. Has a relatively good prognosis. Increased incidence in BRCA1 carriers.

A type of invasive ductal carcinoma characterized by carcinoma in dermal lymphatics. Presents classically as inflamed, swollen breast due to blocked lymphatic drainage with no discrete mass. It can be mistaken for acute mastitis. Has a poor prognosis.

A malignant proliferation of cells in lobules without invasion of the basement membrane. Does not produce a mass or calcifications, usually discovered incidentally on biopsy. Characterized by dyscohesive cells lacking E-cadherin adhesion protein. Often multifocal and bilateral. Treated with tamoxifen and close follow-up. Low risk of progression to invasive carcinoma.

A type of invasive carcinoma that grows in a single-file pattern. Cells may exhibit signet-ring morphology. Lack of duct formation due to lack of E-cadherin.

The most important prognostic factor in breast cancer. Determines the severity and likelihood of spread.

The most useful and commonly assessed prognostic factor in breast cancer, which is often assessed using sentinel lymph node biopsy.

Factors that predict the response to treatment in breast cancer.