Clinical meaning
Breast cancer develops when cells in the breast tissue grow uncontrollably and form a malignant tumor. Most breast cancers begin in the cells lining the milk ducts (ductal carcinoma) or the lobules that produce milk (lobular carcinoma). These abnormal cells accumulate genetic mutations that allow them to divide without normal regulatory control, invade surrounding tissues, and potentially spread (metastasize) to lymph nodes and distant organs. Breast cancer can be classified by its receptor status - whether the cancer cells have receptors for estrogen (ER), progesterone (PR), or the HER2 protein - which determines treatment options. Early detection through screening and self-examination significantly improves outcomes.
Exam relevance
Risk factors: - Female sex (though males can also develop breast cancer) - Age over 50 years - Family history of breast or ovarian cancer (especially first-degree relatives) - BRCA1 or BRCA2 gene mutations - Early menarche or late menopause (prolonged estrogen exposure) - Nulliparity or first pregnancy after age 30 - Hormone replacement therapy - Obesity (postmenopausal) - Alcohol consumption - Prior chest radiation exposure