Oncology
Breast Cancer
유방암
Breast tissue cancer where ER/PR/HER2 molecular subtypes drive treatment
- How common
- Top female cancer (lifetime risk 11% in Korea)
- Typical age
- Ages 40–60
What is it?
Estrogen, BRCA1/2 mutations, and HER2 amplification drive ductal/lobular epithelial transformation.
Commonly affected: Breast (upper-outer 50%), axillary nodes, bone/liver/lung/brain
How it develops
- Initiating factorsEstrogen exposure, BRCA1/2 mutation, radiation
- In situ carcinomaNon-invasive carcinoma confined to ducts/lobules
- Basement membrane invasionHER2/PI3K/CCND1 drive invasive carcinoma
- Lymphatic/hematogenous metsAxillary nodes → bone, liver, lung, brain
Symptoms
- Painless massHard, irregular, fixed
- Nipple discharge/retractionBloody discharge or new retraction
- Skin changesPeau d'orange, erythema, dimpling
- Axillary lymphadenopathyHard, fixed nodes
- Bone pain (mets)Night pain in spine/pelvis
How it is examined
- Breast inspection/palpationSymmetry, skin, masses by quadrant
- Lymph node examAxillary and supraclavicular nodes
- Clinical TNMT (size), N (nodes), M (mets)
Imaging
Mammography: microcalcifications, masses; BI-RADS classification.
- Spiculated mass
- Pleomorphic microcalcifications
- Architectural distortion
Breast MRI for BRCA carriers, dense breasts, multifocality. Diagnosis by core needle biopsy.
- Enhancing mass
- Multifocal disease
- Nodal metastasis
Non-surgical care
- Molecular subtypingER, PR, HER2 (IHC + FISH), Ki-67. Luminal A/B, HER2+, TNBC
- Endocrine therapy (ER+)Premenopausal: tamoxifen; postmenopausal: letrozole/anastrozole x 5–10 yrs
- HER2-targeted therapyTrastuzumab + pertuzumab + chemo; T-DXd in advanced
- ChemotherapyAC-T (doxorubicin/cyclophosphamide → paclitaxel), TC, dose-dense
- CDK4/6 + PARP inhibitorsPalbociclib (HR+); olaparib (BRCA+)
Conservative options are generally tried first. Medications listed here can have side effects — discuss them with your prescriber.
When surgery is considered
All localized breast cancers (per stage and subtype)
Procedures that may be discussed
- Breast-conserving surgery + RT (lumpectomy)
- Mastectomy + reconstruction
- Sentinel lymph node biopsy (SLNB)
- Axillary LN dissection if SLN+
- Neoadjuvant chemo → surgery (cT3, HER2+, TNBC)
Outlook
5-yr survival: localized 99%, regional 86%, distant 30%. Subtype is a strong prognostic factor.