Clone 1d5

Pathological diagnosis was performed by the Department of pathology, Ruijin Hospital. IHC studies of ER, PR, HER2, and Ki-67 were performed on formalin-fixed, paraffin-embedded tissue sections, using antibodies as follow: ER: clone 1D5 (rabbit monoclonal, Gene), PR: clone PR636 (mouse monoclonal, Dako), HER2: 4B5 (rabbit monoclonal, Roche), Ki67: MIB-1 (mouse monoclonal, Dako). Hormone receptor including ER and PR were considered positive if nuclear staining in ≥1% of tumor cells. 0 to 1+ by IHC or negative on FISH was recognized as HER2 negativity. Ki67 index was characterized as the proportion of positive nuclear staining cells among ≥1,000 invasive tumor cells. The cut-off values for ER expression was 50% (12 (link)), which was 20% for PR status (13 (link)) and 14% for Ki-67 index (13 (link)). Luminal A-like was identified if IHC shows ER positive, PR ≥20% and Ki-67 <14%, and Luminal B-like was defined as ER positive, and PR <20% or Ki-67 ≥14% (13 (link)).

Positive staining for ER/PR was defined as nuclear staining in ≥1% of the tumor cells. Negative HER2 status was considered as 0 to 1+ by IHC or negative on FISH. Ki-67 index was characterized as the proportion of positively nuclear staining cells among at least 1000 tumor cells in the area counted. The following antibodies were used for the IHC test: ER: clone 1D5 (rabbit monoclonal, Gene), PR: clone PR636 (mouse monoclonal, Dako), HER2: 4B5 (rabbit monoclonal, Roche), Ki67: MIB-1 (mouse monoclonal, Dako).