Table 1 Overview of the design and most important results of studies focusing on the prognostic and/or predictive value of basal cytokeratin
expression in invasive breast cancer
| Authors | Source of tissue | Clinical data | Type of basal cytokeratin | Threshold for the expression of basal cytokeratins | Conclusion | |||||
| Rakha et al51 | TMA | Not specified in detail | Ck 5/6 and/or Ck 14 | 10% | Expression of Ck 5/6 and/or Ck 14 is sufficient for the definition of basal breast cancer | |||||
| Jumpannen et al40 | TMA | No adjuvant treatment | Ck 5/Ck 14/p63 antibody cocktail | 20% | No impact on overall survival in ER-negative breast cancers | |||||
| Abd El-Rehim et al28 | TMA | Not specified in detail | Ck 5/6 and/or Ck 14 | Any positive cell | Expression of basal cytokeratins is an independent prognostic marker At least four different immunohistochemical phenotypes can be defined | |||||
| Laakso et al39 | Tissue sections | (a) without adjuvant treatment (b) dose-escalated adjuvant chemotherapy | Ck 5/Ck 14/p63 antibody cocktail | 5% 70% for the “true” basal subtype | The true basal breast cancer subtype in contrast to the basoluminal subtype is not associated with HER2-amplifications and showed a significantly different prognosis No prognostic value of the expression of basal cytokeratins in high-risk patients | |||||
| Van de Rijn et al79 | TMA | Patients with and without adjuvant chemotherapy, and anti-hormone therapy, respectively | Ck 17 and/or Ck 5/6 | Invasive tumour cells with strong staining | Basal cytokeratin expression was an independent prognostic marker in node-negative breast cancer | |||||
| Nielsen et al45 | TMA | Patients with adjuvant and neoadjuvant chemotherapy, anti-hormone therapy, respectively | Ck 17 and/or Ck 5/6 | Invasive tumour cells with <20% of weak staining | A panel of 4 antibodies (ER, Ck 5/6, HER2 and EGFR) can accurately identify basal-like tumours | |||||
| Jones et al38 | Tissue sections of grade 3 breast cancers | Not specified in detail | Ck 14 | Any positive cell | Basal carcinomas have a decreased overall survival and show a distinct chromosomal alteration pattern | |||||
| Fulford et al42 | Tissue sections of grade 3 breast cancers | Not specified in detail | Ck 14 | At least 1% of invasive tumour cells | Basal carcinomas develop less bone and liver metastasis. Overall survival was improved in basal grade 3 carcinomas compared to non-basal grade 3 carcinomas. In metastatic disease the prognosis was decreased | |||||
| Banerjee et al80 | Tissue sections of grade 3 breast cancers | Not specified in detail | Ck 5/6, Ck 14, Ck 17 | Any positive cell | Significantly increased recurrence rate and overall survival Adjuvant anthracyline-based chemotherapy seems less effective compared to grade matched controls |
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TMA, tissue microarray.
