Breast cancer is a highly heterogeneous tumor, and its classification and diagnosis rely on the comprehensive evaluation of molecular markers and pathological morphology. According to St. Gallen Consensus or WHO classification, there are 4 subtypes of breast cancer.

Luminal A type

• Accounting for 40-50% of the total number of breast cancer.
• Markers: ER (+), PR (+), HER2 (-), Ki67 with low expression (usually < 20%).
• Characteristics: It is the most common type of breast cancer. Its growth depends on hormones, and it is sensitive to endocrine therapy. It has the best prognosis, and it occurs more frequently in elderly patients.
• Detection method: Immunohistochemistry (IHC). The positive threshold is usually: in the sample, ≥1% of tumor cells are stained.

Luminal B type

• Accounting for 20-30% of the total number of breast cancer.
• HER2 negative type: ER (+), PR (low expression or -), HER2 (-), Ki67 high (≥20%).
• HER2 positive type: ER (+), HER2 (+) (with any status of PR or Ki67).
• Characteristics: The tumor growth is hormone-dependent, and its invasiveness is higher than that of the Luminal A type. It requires endocrine therapy with or without chemotherapy, and the prognosis is moderate.
• Detection method: Immunohistochemistry (IHC). The positive threshold is usually: in the sample, ≥1% of tumor cells are stained.

HER2 overexpression type

• Accounting for 15-20% of the total number of breast cancer.
• Markers: ER (-), PR (-), HER2 (+)
• Characteristics: It has strong invasiveness, and anti-HER2 targeted therapies (such as trastuzumab and pertuzumab) have remarkable effects.
• Detection method:

1. HER2 IHC: 0/1+ (negative), 2+ (requiring FISH verification), 3+ (positive).
2. HER2 FISH: A HER2/CEP17 ratio ≥ 2.0 or a HER2 copy number ≥ 6.0 is considered positive.

Triple-negative breast cancer (TNBC)

• Accounting for 10-15% of the total number of breast cancer.
• Markers: ER (-), PR (-), HER2 (-)
• Characteristics: It is the most invasive, prone to early metastasis. The treatment depends on chemotherapy. It is more commonly seen in young women (< 50 years old) and carriers of BRCA mutations, and has a poor prognosis.

Other commonly used diagnostic markers

• Ki67: It reflects the proliferative activity of tumor cells. A high Ki67 level (≥20%) indicates a poor prognosis and it may require intensified treatment.
• Basal cell markers: CK5/6 and EGFR

It is commonly used for the further classification of triple-negative breast cancer (TNBC). A positive result suggests it may be the "Basal-like" type, which is more invasive.

The Basal-like type overlaps with TNBC, and approximately 80% of TNBC cases are of the Basal-like type.

Diagnostic process

1， Biopsy: To confirm invasive carcinoma or carcinoma in situ.

2， Immunohistochemistry: To detect ER, PR, HER2 and Ki67.

3， FISH (when necessary): When the HER2 IHC result is 2+, FISH is required for confirmation.

4， Supplementary tests for TNBC: CK5/6, EGFR, PD-L1, etc.

5， Genetic testing (optional): To assess the recurrence risk or BRCA mutation testing.

We, Dartmon, provide the best-in-class antibodies for breast cancer diagnosis.

ER Antibody

Cat. No. : DMRD0191

Usage pattern: Manual or device utilization

Ready-to-use: 3ml, 6ml, 10ml

Concentrated: 0.1ml, 0.5 ml, 1ml

PR Antibody

Cat. No. : DMRD0249

Usage pattern: Manual or device utilization

Ready-to-use: 3ml, 6ml, 10ml

Concentrated: 0.1ml, 0.5 ml, 1ml

EGFR Antibody

Cat. No. : RMF1A066

Usage pattern: Manual or device utilization

Ready-to-use: 3ml, 6ml, 10ml

Concentrated: 0.1ml, 0.5 ml, 1ml

Ki67 Antibody

Cat. No. : RMA1A020

Usage pattern: Manual or device utilization

Ready-to-use: 3ml, 6ml, 10ml

Concentrated: 0.1ml, 0.5 ml, 1ml

HER2 Antibody

Cat. No. : DMRD0203

Usage pattern: Manual or device utilization

Ready-to-use: 3ml, 6ml, 10ml

Concentrated: 0.1ml, 0.5 ml, 1ml

CK5/6 Antibody

Cat. No. : RMB1A014

Usage pattern: Manual or device utilization

Ready-to-use: 3ml, 6ml, 10ml

Concentrated: 0.1ml, 0.5 ml, 1ml