Breast cancer

Disease Description (Causes and Symptoms)

• Definition: A malignant neoplasm arising from the epithelium of the mammary ducts or lobules (breast cancer). It develops through the combined effects of genetic, hormonal, and environmental factors.
• Main causes and risk factors: Age (risk increases after the 40s), family history (breast cancer in a first-degree relative), early menarche (e.g., before age 14), late menopause (e.g., after age 50), no childbirth or late first full-term childbirth, no history of breastfeeding, obesity, and a Westernized high-calorie, high-fat diet. Some cases are associated with genetic mutations such as BRCA1/2.
• Pathophysiology (summary): Genetic mutations in ductal or lobular epithelial cells disrupt the regulation of growth and division, leading to tumor formation. The status of estrogen and progesterone receptors (ER/PR) and whether HER2 is expressed play important roles in determining treatment and prognosis.
• Main symptoms:
  • A palpable lump in the breast (often painless)
  • Nipple discharge (which may be bloody)
  • Enlarged axillary lymph nodes (a lump in the armpit)
  • Dimpling, redness, or swelling of the breast skin (findings of inflammatory breast cancer)
  • Breast pain is relatively nonspecific

Treatment Methods and Precautions

• Basic treatment principles: Individualized multidisciplinary treatment (surgery, radiation therapy, and systemic therapy) is planned according to the stage (whether localized or metastatic), histologic type, hormone receptor status, and HER2 status.
• Surgery:
  • Breast-conserving surgery (partial mastectomy) + radiation therapy: Considered preferentially when the ratio of tumor size to breast size is acceptable.
  • Total mastectomy (removal of the entire breast): Selected when the extent of the lesion is broad or when there is a risk of recurrence, among other circumstances.
  • Lymph node evaluation: Begins with sentinel node biopsy; if metastasis is confirmed, axillary lymph node dissection is performed.
  • Breast reconstruction: Immediate or delayed reconstruction is possible (using implants or autologous tissue).
• Radiation therapy:
  • Standard treatment after breast-conserving surgery. Adjuvant radiation therapy is considered for high-risk patients after total mastectomy.
  • Side effects: Skin reactions, fatigue, localized swelling, and, rarely, long-term complications.
• Systemic therapy:
  • Chemotherapy (to shrink the tumor before treatment [neoadjuvant therapy] or as adjuvant therapy after surgery)
  • Hormone therapy: Tamoxifen (with consideration of premenopausal or postmenopausal status) or aromatase inhibitors (after menopause) is used in patients who are ER/PR-positive.
  • Targeted therapy: For HER2-positive cases, anti-HER2 treatment such as trastuzumab is used (a key component of breast cancer treatment).
  • Recent targeted and immunotherapies (e.g., CDK4/6 inhibitors, PIK3CA-targeted agents, and immune checkpoint inhibitors) are used for certain subtypes and conditions.
• Supportive care and rehabilitation:
  • Management of nausea and vomiting and fatigue caused by chemotherapy, and prevention of infection (e.g., G-CSF in cases of leukopenia)
  • Prevention and management of lymphedema (exercise, compression, skin care, and weight management)
  • Osteoporosis management: When using aromatase inhibitors, bone mineral density monitoring and calcium and vitamin D supplementation; antiresorptive agents may be considered when necessary
• Main precautions/complications:
  • Lymphedema (swelling of the arm after surgery or radiation therapy)
  • Bone marrow suppression, hair loss, nausea, and cardiotoxicity related to chemotherapy and targeted therapy (especially anthracyclines and trastuzumab) — cardiac function monitoring is necessary
  • Tamoxifen: Increased risk of thrombosis and endometrial cancer (regular gynecologic examinations are recommended)
  • Aromatase inhibitors: Joint pain and osteopenia
  • Radiation-related skin reactions and fatigue

Checkpoints Before an Outpatient Visit (Including Example Questions)

• Items/documents to prepare or submit:
  • A list of all medications currently being taken (including prescription and nonprescription drugs, herbal medicines, and supplements)
  • Past medical history and surgical history, and family history (especially breast or ovarian cancer)
  • Recent mammography, breast ultrasound, biopsy results and reports, and surgical or treatment records (if available)
  • Menstrual and menopausal status (last menstrual period, follicle-stimulating hormone status, etc.) and pregnancy plans (if of childbearing age)
  • Weight and height (whether obese), and lifestyle habits (smoking, alcohol consumption, and exercise)
• Symptom records to tell the doctor during the outpatient visit:
  • The lump's size, when it was discovered, and whether it has changed; nipple discharge (color and amount); breast skin changes; and whether pain is present
  • Systemic symptoms (fever, weight loss, shortness of breath, etc.)
• Example questions (questions the patient should prepare in advance to ask the doctor):
  • "Do I need to stop any of the medications I am currently taking?"
  • "What are the main findings identified in my current test results (imaging and biopsy)?"

General Example Questions to Ask the Doctor

• What is the goal of this medication (or treatment), and what side effects are expected?
• What is the stage of my cancer, and what is the prognosis? How will regular follow-up be conducted?
• What lifestyle guidelines should I follow to prevent lymphedema after surgery?
• If pregnancy or fertility preservation is needed, what options (such as sperm or egg preservation and ovarian suppression) should be considered?

Examples of Disease-Specific Questions

• What are the hormone receptor (ER/PR) and HER2 statuses of my cancer? How will these results affect future treatment (hormone therapy and targeted therapy)?
• If the sentinel lymph node biopsy result is negative, is additional axillary dissection unnecessary? If I want reconstructive surgery, how will the timing and method be determined?

(Note: The information above has been compiled for general educational purposes. Decisions regarding an individual's diagnosis and treatment should be made in consultation with the treating medical team, taking into account the stage, histologic findings, and overall condition.)