Immunocytochemical staining of c‐erbB‐2 oncogene in fine‐needle aspirates of breast carcinoma: A comparison with tissue sections and other breast cancer prognostic factors

The role of fine‐needle aspiration (FNA) in breast cancer management is expanding to include prognostic in addition to diagnostic studies. This study was undertaken to compare the immunohistochemical staining of c‐erbB‐2, a breast cancer prognostic factor, on cytologic FNA smears of breast cancer with that on corresponding formalin‐fixed, paraffin‐embedded tissue sections of the same tumor and to correlate the c‐erbB‐2 expression with other known breast cancer prognostic factors. FNA smears (destained, alcoholfixed, Pap‐stained direct smears) and corresponding tissue sections (formalin‐fixed, paraffin‐embedded, unstained sections) from 36 primary breast carcinomas were stained immunohistochemically with c‐erbB‐2 antibody using an avidin‐biotin procedure. Ten tumors (28%) showed strong positive staining for c‐erbB‐2 on the FNA smear and, of those ten, seven were positive on the corresponding tissue section and three were negative. In several of the cytology and tissue positive cases, staining on the tissue section was significantly weaker than on the FNA smear. Two cases involved treatment with preoperative chemotherapy; in one of those cases, tissue staining was weaker than cytologic staining, and, in the other case, both were negative. Correlation of c‐erbB‐2 staining with other prognostic factors showed an association between positive c‐erbB‐2 staining and high nuclear grade. Our results indicate that immunohistochemical staining for c‐erbB‐2 can be performed on destained FNA smears of breast carcinomas and may be more sensitive on the cytologic specimens than on formalin‐fixed, paraffin‐embedded tissue sections. Diagn Cytopathol 1994;11:250–254. © 1994 Wiley‐Liss, Inc.