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Updated: Jun 20, 2026
Studying Triple Negative Breast Cancer Using Orthotopic Breast Cancer Model
Published on: March 20, 2020
Clinical significance of basal-like subtype in triple-negative breast cancer
Yutaka Yamamoto1, Mutsuko Ibusuki, Masahiro Nakano
1Department of Breast and Endocrine Surgery, Kumamoto University Graduate School of Medical Sciences, 1-1-1 Honjo, Kumamoto, Kumamoto 860-8556, Japan. ys-yama@triton.ocn.ne.jp
Background:
No clinically useful target molecule has been identified for triple-negative (TN) breast cancer, i.e., estrogen receptor (ER)-negative, progesterone receptor (PgR)-negative, human epidermal growth factor receptor-2 (HER2)-negative phenotype, and its prognosis is poor. Triple-negative cancer consists of two subtypes: basal-like and non-basal-like. The aim of this study is to clarify the clinical and biological characteristics of these two subtypes of TN cancer.
Methods:
We examined, by immunohistochemistry, expression of biological markers cytokeratin (CK) 5/6 and epidermal growth factor receptor (EGFR) in triple-negative breast cancer. Basal-like subtype was defined as CK5/6-positive and/or EGFR-positive, and non-basal-like subtype was defined as no expression of these two markers. We studied the correlation between basal-like subtype and several factors related to tumor progression, along with the prognostic value of basal-like subtype and other biological markers in triple-negative cancer.
Results:
In the 48 cases of operable triple-negative breast cancer, basal-like subtype was detected in 22 (45.8%) and non-basal-like subtype in 26 (54.2%). Basal-like subtype was significantly correlated with nodal status (P = 0.0475) and nuclear grade (P = 0.0475). Basal-like subtype was also significantly associated with Ki67 labeling index (P = 0.0118), c-kit expression (P = 0.0335), and aurora A expression (P = 0.0020). No association was detected between basal-like cancer and other biological markers. Patients with basal-like subtype of triple-negative cancer showed shorter disease-free survival (P = 0.0049) and overall survival (P = 0.0283) than patients with non-basal-like subtype. No independent prognostic factors were identified among the prognostic factors obtained from univariate analysis.
Conclusions:
These findings suggest that basal markers can be used to classify triple-negative breast cancer into at least two subtypes with differing prognoses. It is necessary to develop a novel treatment strategy to improve the prognosis of patients with basal-like subtype of triple-negative breast cancer.
Insights
Triple-negative breast cancer (TNBC) can be classified into basal-like and non-basal-like subtypes using basal markers. The basal-like subtype is associated with poorer prognosis and shorter survival in TNBC patients.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Triple-negative breast cancer (TNBC) lacks clinically useful therapeutic targets, leading to poor patient prognosis.
- TNBC is heterogeneous, comprising basal-like and non-basal-like subtypes.
- Identifying distinct subtypes is crucial for understanding TNBC biology and improving treatment strategies.
Purpose of the Study:
- To investigate the clinical and biological characteristics of basal-like and non-basal-like TNBC subtypes.
- To determine the correlation between the basal-like subtype and tumor progression factors.
- To evaluate the prognostic significance of the basal-like subtype in TNBC.
Main Methods:
- Immunohistochemistry was used to assess the expression of cytokeratin (CK) 5/6 and epidermal growth factor receptor (EGFR) in 48 operable TNBC cases.
- Basal-like subtype was defined by positive CK5/6 and/or EGFR expression.
- Non-basal-like subtype was defined by the absence of both CK5/6 and EGFR expression.
Main Results:
- The basal-like subtype was identified in 45.8% of TNBC cases, while the non-basal-like subtype was found in 54.2%.
- Basal-like subtype showed significant correlations with nodal status, nuclear grade, Ki67 labeling index, c-kit, and aurora A expression.
- Patients with basal-like TNBC exhibited significantly shorter disease-free and overall survival compared to those with non-basal-like TNBC.
Conclusions:
- Basal markers effectively classify TNBC into subtypes with distinct prognoses.
- The basal-like subtype of TNBC is associated with a poorer clinical outcome.
- Novel therapeutic strategies are needed to improve the survival rates for patients with basal-like TNBC.