ESSENTIALS OF DIAGNOSIS
Risk factors: Age, nulliparity, childbirth after age 30, family history of breast cancer or genetic mutations (BRCA1, BRCA2), and personal history of breast cancer or some types of proliferative conditions.
Early findings: Single, nontender, firm to hard mass with ill-defined margins; mammographic abnormalities and no palpable mass.
Later findings: Skin or nipple retraction; axillary lymphadenopathy; breast enlargement, erythema, edema, pain; fixation of mass to skin or chest wall.
Breast cancer will develop in one of eight American women. Next to skin cancer, breast cancer is the most common cancer in women; it is second only to lung cancer as a cause of death. In 2018, there were approximately 268,670 new cases and 41,400 deaths from breast cancer in the United States. Worldwide, breast cancer is diagnosed in approximately 2.1 million women, and about 626,679 die of breast cancer each year, with the highest rates of diagnosis in Australia/New Zealand, Europe, and North America and lowest rates in Eastern/Middle Africa and South Central Asia. The highest rates of death are in black women in the United States and the lowest rates are in Korean women. These regional differences in incidence are likely due to the variable availability of screening mammography as well as differences in reproductive, nutrition and hormonal factors. In western countries, incidence rates decreased with a reduced use of postmenopausal hormone therapy and mortality declined with increased use of screening and improved treatments. In contrast, incidence and mortality from breast cancer in many African and Asian countries have increased as reproductive factors have changed (such as childbirth after age 30) and as the incidence of obesity has risen.
The most significant risk factor for the development of breast cancer is age. A woman’s risk of breast cancer rises rapidly until her early 60s, peaks in her 70s, and then declines. A significant family history of breast or ovarian cancer may also indicate a high risk of developing breast cancer. Germline mutations in the BRCA family of tumor suppressor genes or other breast cancer susceptibility genes accounts for approximately 5–10% of breast cancer diagnoses and tend to cluster in certain ethnic groups, including women of Ashkenazi Jewish descent. Women with a mutation in the BRCA1 gene, located on chromosome 17, have an estimated 85% chance of developing breast cancer in their lifetime. Other genes associated with an increased risk of breast and other cancers include BRCA2 (associated with a gene on chromosome 13); ataxia-telangiectasia mutation (ATM), BARD1, CHEK2, PALB2, RAD51D; and mutation of the tumor suppressor gene p53. If a woman has a compelling family history (such as breast cancer diagnosed in two first-degree relatives, especially if diagnosed younger than age 50; ovarian cancer; male breast cancer; or a first-degree relative with bilateral breast cancer), genetic testing may be appropriate. In general, it is best for a woman who has a strong ...