Overview
Definition
A malignant proliferation of epithelial cells lining the ducts or lobules of the breast.
Epidemiology
The most commonly diagnosed cancer in women worldwide. Lifetime risk for women is ~1 in 8.
Etiology & Risk Factors
- Genetic mutations (BRCA1, BRCA2 accounts for 5-10% of cases)
- Prolonged estrogen exposure: Early menarche, late menopause, nulliparity, HRT use
- Increasing age and obesity
Clinical Symptoms
- Painless, hard, fixed breast mass (most common presentation)
- Skin changes: Dimpling, nipple retraction, 'Peau d'orange' (orange peel skin - a sign of Inflammatory Breast Cancer)
- Bloody or spontaneous nipple discharge
- Axillary lymphadenopathy
Clinical Approach
Diagnosis
- Mammogram: Screening and initial diagnostic test (looks for clustered microcalcifications or spiculated masses)
- Ultrasound: Used in younger women (< 30) with dense breasts, or to differentiate cystic vs solid masses
- Core Needle Biopsy (Gold Standard): Defines histology (e.g., Invasive Ductal Carcinoma is most common) and receptor status (ER, PR, HER2)
Management
- Surgery: Lumpectomy with radiation OR Mastectomy, PLUS Sentinel Lymph Node Biopsy
- Systemic therapy depends on receptor status:
- Hormone Receptor (ER/PR) Positive: Endocrine therapy (Tamoxifen for premenopausal, Aromatase Inhibitors for postmenopausal)
- HER2 Positive: Trastuzumab (Herceptin)
- Triple Negative (ER/PR/HER2 negative): Chemotherapy is the mainstay
Complications
- Metastasis (Bone, Lungs, Liver, Brain)
- Lymphedema (swelling of the arm following axillary lymph node dissection)