Chapter 60: Breast Cancer

INTRODUCTION

• Breast cancer is a malignancy originating from breast tissue. Disease confined to a localized breast lesion is referred to as early, primary, localized, or curable. Disease detected clinically or radiologically in sites distant from the breast is referred to as advanced or metastatic breast cancer (MBC), which is usually incurable.

EPIDEMIOLOGY

• Two variables most strongly associated with occurrence of breast cancer are gender and advancing age. Additional risk factors include endocrine factors (eg, early menarche, nulliparity, late age at first birth, and hormone replacement therapy), genetic factors (eg, personal and family history, mutations of tumor suppresser genes [BRCA1 and BRCA2]), and environmental and lifestyle factors (eg, radiation exposure).

• Breast cancer cells often spread undetected by contiguity, lymph channels, and through the blood early in the course of the disease, resulting in metastatic disease after local therapy. The most common metastatic sites are lymph nodes, skin, bone, liver, lungs, and brain.

PREVENTION OF BREAST CANCER

• SERMs and AIs are being studied for pharmacologic risk reduction of breast cancer.

• The most clinical information is available for the SERMs, tamoxifen and raloxifene, which reduce the rates of invasive breast cancer in women at high risk for developing the disease. Rates of endometrial cancer and deep vein thromboses are higher in patients receiving tamoxifen, but the overall quality of life is similar between the two agents.

• Exemestane taken for 5 years significantly reduced the rates of invasive breast cancers with tolerable adverse events.

• Risk reduction strategies include mastectomy, oophorectomy, and pharmacologic agents. Clinical guidelines recommend the use of tamoxifen, raloxifene, or exemestane for postmenopausal women at high risk and tamoxifen for premenopausal women at high risk based on the woman’s wishes.

CLINICAL PRESENTATION

• A painless, palpable lump is the initial sign of breast cancer in most women. The typical malignant mass is solitary, unilateral, solid, hard, irregular, and nonmobile. Nipple changes are less commonly seen. More advanced cases present with prominent skin edema, redness, warmth, and induration.

• Symptoms of MBC depend on the site of metastases but may include bone pain, difficulty breathing, abdominal pain or enlargement, jaundice, and mental status changes.

• Many women first detect some breast abnormalities themselves, but it is increasingly common for breast cancer to be detected during routine screening mammography in asymptomatic women.

DIAGNOSIS

• Initial workup should include a careful history, physical examination of the breast, three-dimensional mammography, and, possibly, other breast imaging techniques, such as ultrasound and magnetic resonance imaging (MRI).

• Breast biopsy is indicated for a mammographic abnormality that suggests malignancy or for a palpable mass on physical examination.

STAGING

• Stage (anatomical extent of disease) is based on primary tumor extent and size (T_1–4), presence and extent of lymph node involvement ...