Breast Cancer

Introduction

• Description: Breast cancer is a malignant neoplasm of the breast that is classified with respect to the cell type, location, and degree of invasion. Breast cancer is the second most common malignancy in women (second to skin cancers), accounting for almost one-third of all women’s malignancies. Breast cancer accounts for approximately 18% of cancer deaths (second to lung cancer) and results in approximately the same number of deaths per year as auto accidents.

• Prevalence: Lifetime risk of one in eight by the age of 90 years; lifetime risk of death is 13%; more than 287,850 new cases and 43,250 deaths annually (2022).

• Predominant Age: Of all breast cancer cases, 85% occur after the age of 40 years and 75% occur after the age of 50 years, median age 62 years.

• Genetics: Women with BRCA1 mutations have a 60% lifetime risk for breast cancer ( BRCA2 mutations carry an 85% risk for breast cancer and up to 20% risk for ovarian cancer). Only 5%–10% of patients with breast cancer have a family history of breast cancer. African-American women have a lower incidence of breast cancer, but they have a higher mortality rate. Mutations in other genes ( ATM, TP53, CHEK2, PTEN, and others) also may convey increased risk.

Etiology and Pathogenesis

• Causes: Unknown.

• Risk Factors: First-degree relative with breast cancer (relative risk [RR] = 2.3; RR = 10.5 with bilateral disease), moderate alcohol use (3–5 drinks/day, RR = 1.41), early menarche, late menopause, nulliparity, or late first pregnancy (older than 30 years), prior history of breast cancer (5%/year), estrogen use (RR = 1.12). Only 21% of patients with breast cancer who are aged 30–54 years are identified by risk factors. Abortion, caffeine use, and breast implants do not affect the risk for breast cancer.

Signs and Symptoms

• Palpable mass (55%); 60% located in the upper outer quadrant of the breast

• Abnormal mammogram without a palpable mass (35%)

• Skin change—color or dimpling (peau d’orange)

• Nipple retraction, nipple discharge (bloody or otherwise]), skin changes, or ulceration are late occurrences and portend a bad prognosis

• Axillary mass

• Breast pain is present in fewer than 10% of women with early breast cancer

Diagnostic Approach