Besides, immunohistochemistry still remains the gold standard for estimation of ER status in breast cancer. Although, as stated by Reis-Filho and Tutt, “”from a scientific perspective, microarray-based expression profiling analysis remains the gold standard for the identification of basal breast cancers”", stringent analysis of profiles discloses that in basal-like cases there is low expression

of basal cytokeratins in a few cases [2–4]. Similarly, in some luminal-type tumors there are cases with high expression of CK5 or CK14 [2, 3]. As mRNA for basal-type cytokeratins may originate from myoepithelial cells forming normal breast tissue intermixed with cancer cell, or the number of cancer cells even presenting these cytokeratins may be to sparse — in both situations false results may be obtained. The aim of this Bcl-2 inhibitor retrospective Selleck Idelalisib study was to compare basal-cell-type cytokeratin expression estimated by real-time RT-PCR and by a routine immunostaining. Patients and Methods Tumor specimens and study patients Specimens of primary tumors were consecutively obtained from 115 women with operable invasive ductal carcinomas not otherwise specified (NOS) at a time of routine surgery at the Oncology Department of Copernicus Memorial Hospital in Lodz, Poland, between 1998 and 2001. In all cases, surgical

procedure was a radical mastectomy with axillary lymph node dissection. Serial sections of the tumor were obtained from archived paraffin embedded tissue blocks. The primary pathologic diagnosis was confirmed in H&E staining. Subsequent slides were stained for ER and HER2. For further mRNA analysis, fresh tumor specimens were frozen immediately

after excision at -80°C. Patient characteristics are presented in table 1. Table 1 Patient characteristics Factor Number of patients Number of patients 115 Age (years)   ≤ 50 39 (33,9%) > 05 76 (66,1%) Tumour   T1 33 (28,7%) T2-4 82 (71,3%) Nodal status   Positive 56 (48,7%) Negative 59 (51,3%) Grade   G1-2 63 (54,8%) G3 52 (45,2%) ER status   Positive 60 (52,2%) Negative 55 (47,8%) CK5/6 status (IHC)   Positive 42 (36,5%) Negative 73 (63,5%) CK14 status (IHC)*   Positive 16 (14,0%) Negative 98 (86,0%) CK17 status (IHC)   Positive 29 (25,2%) Negative 86 (74,8%) Adjuvant treatment      Chemotherapy check 66 (57,4%)    Hormonotherapy 82 (71,3%)    Radiotherapy 21 (18,3%)    Missing data 8 (7,0%) * In one sample assessment was not possible due to technical reasons Immunohistochemistry and scoring Paraffin embedded sections were routinely processed. Slides for immunostaining for ER (Dako), CK14 and CK17 (both Novocastra) were pretreated with citrate buffer in a microwave oven. CK5/6 antibody from Dako was applied following autoclaving with high pH buffer. Antibody dilutions were as follows: ER – 1:35, CK5/6 – 1:100, CK14 — 1:20, CK17 – 1:40. All following procedures were done according to standard protocols with EnVision+ System HRP (Dako).