IHC breast cancer phenotype detail

Luminal A:
ER(+) PR(+/-) HER2(-) Ki67(-) (<14%)
Luminal A phenotypes are the most common (42% to 59%), are of low to moderate histological grade, and have long survival and low recurrence rates. This phenotype has the best prognosis and occurs mostly in elderly patients.
Luminal B (HER2 negative):
ER(+) PR(+/-) HER2(-) Ki67(+) (>14%)
Luminal B (HER2 negative) phenotypes are typically diagnosed at a younger age, are of higher histological grade, have a larger tumor size at the time of diagnosis, and may present with p53 mutations. Survival rates are high, but not as high as those of patients with Luminal A tumors.
Luminal B (HER2 positive):
ER(+) PR(+/-) HER2(+)
Luminal B (HER2 positive) phenotypes have a more aggressive clinical course, typically with a high recurrence rate when evaluated by a genomic assay for prediction of 10 year risk of local recurrence (Oncotype DX®). This phenotype is usually present in younger patients and may confer less responsiveness to tamoxifen.
HER2 Overexpressing:
ER(-) PR(+/-) HER2(+)
HER2 overexpressing or classic phenotypes are more likely to respond to anthracyclines and exhibit good response to trastuzumab (Herceptin®) in combination with chemotherapy. HER2 overexpressing tumors which are ER+/HER2+ may demonstrate tamoxifen resistance.
Triple-Negative Basal-Like:
ER(-) PR(-) HER2(-) CK 5/6(+) and/or EGFR(+)
The name for basal-like tumors is derived from the tumor cells themselves, reminiscent of normal myoepithelial cells (basal cells) lining the breast ducts when analyzed by gene expression profiling (GEP). This phenotype has an aggressive clinical course and poor prognosis. Part of a group of triple negative breast cancers (ER-, PR-, HER2-), they demonstrate an increase in early systemic recurrence with visceral and brain metastasis. Patients with BRCA1 mutations typically develop basal-like tumors.
Triple-Negative Non-Basal:
ER(-) PR(-) HER2(-) CK 5/6(-) and EGFR(-)
Non-basal tumors are part of the group of triple negative breast cancers (ER-, PR-, HER2-) by GEP. This phenotype composes a small percentage of triple-negative tumors and have a favorable prognosis.

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Additional detail

  1. Perou CM, Sorlie T, Eisen MB, et al. Molecular portraits of human breast tumors. Nature. 2000;406:747-752.
  2. Weigelt B, Baehner FL, Reis-Filho JS. The contribution of gene expression profiling to breast cancer classification, prognostication and prediction: A retrospective of the last decade. J Pathol. 2010;220:263-280.
  3. Parise CA, Caggiano V. Breast cancer survival defined by the ER/PR/HER2 subtypes and a surrogate classification according to tumor grade and immunohistochemical biomarkers. J Cancer Epidemiol. 2014;2014:469251.
  4. Prat A, Adamo B, Cheang MC, Anders CK, Carey LA, Perou CM. Molecular characterization of basal-like and non-basal-like triple-negative breast cancer. Oncologist. 2013;18(2): 123-33.
  5. Sunil B, et. al. Basal-like and triple-negative breast cancers: A critical review with an emphasis on the implications for pathologists and oncologists. Mod Pathol. 2011;24(2): 157-167.
Specimen Requirements: Formalin-fixed paraffin embedded (FFPE) block
Turnaround Time: 24-48 hours

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