Classification
- Hormone receptor positive vs. negative
- Positive : Luminal epithelial mammary cell like manifestation
- Luminal A, B
- Negative : 3 group
- HER2-enriched
- Basal-like : Basal/myoepithelial (15% )
- 77 % : Triple-negative cancers (71% of them)
- CK5/6, EGFR (+/+) : basal marker
- CK5/6, EGFR (-/-) : quintuple-negative
- Normal-like : Mammary stromal cells
- Positive : Luminal epithelial mammary cell like manifestation
- 1) Luminal A
- Most common (50~60% of all breast cancers)
- High expression of ER and PR
- No expression of HER 2
- Low Ki-67 proliferation index (<15-20%)
- Most favorable prognosis, 5YSR more than 80%
- Favorable response to hormonal therapy
- Usually less responsive to (neo)adjuvant CTx
- 2) Luminal B
- Low expression of ER and PR
- Variable expression of HER2
- High Ki-67 proliferation index
- Usually mid- to high-grade tumors
- Poorer prognosis than luminal A tumors, 5YSR 40%
- Typically responsive to hormonal therapy, possibly less so than luminal A cancers
- High pCR rate to neoadjuvant CTx and possibly more sensitive to adjuvant CTx than luminal A cancers
- 3) HER-2 positive cancer (HER2-Enriched breast carcinoma)
- 15~30%
- ER(-), PR(-), HER-2(+)
- High Ki-67 proliferation
- TP53 gene mutation: high grade, aggressive behavior, worse prognosis
- Intermediate- to high-grade tumor, 5YSR 31% and a high recurrence rate
- Metastases, brain, liver > bone
- Treatment: trastuzumab (Herceptin)
- Imaging
- MMG: irregular mass with spiculated margin, Ca
- US: irregular mass with Ca, indistinct, microlobultaed, spiculated margin
- MR: Irregular enhancing mass with spiculated margin, T2 high
- 4) Triple-negative breast cancer (TNBC)
- ER(-), PR(-), HER2(-) = basal-like breast cancer
- Imaging
- MMG: Round, oval or lobular mass with indistinct margin, Ca infrequent
- US: Circumscribed mass, marked hypoechoic, posterior acoustic enhancement
- MR: Round or oval, T2 high, rim enhancement, enhancing internal septa
*Simulate benign mass on MMG and US
- Clinical issue
- Palpable mass, young premenopausal women
- High nuclear grade
- Aggressive clinical behavior, poor clinical outcome
- Larger size, high grade, necrosis
- Often seen in BRCA 1 mutation carriers
- High risk of early local and distant metastasis (lung, brain)
- Treatment: Chemotherapy, RTx, surgery
