Predictive markers in primary breast cancer compared with lymph node and bloodspread metastases.

High levels of HER2 expression identify those patients who might benefit from treatments that target HER2. Among women with metastatic breast cancer, the predictive markers may be different from the primary tumor. We compared predictive markers: Estrogen Receptor (ER), Progesterone Receptor (PR) and HER2 of primary breast carcinomas with those of lymph node (LN) and blood spread metastases (BM). ER, PR and HER2 status were compared between the primary breast tumor and the LN metastasis and blood spread metastasis. ER, PR and HER2 were performed on primary tumor core biopsies and available FNA cell blocks and on metastatic lesions using FDA approved antibodies and HercepTest (Dako). ER and PR were positive when >/=10%. Her2 was positive (amplified/expressed) when 3+ >30% by immunostain or >2.2 by FISH. Sixty four metastatic breast cancer patients were included in this analysis. Forty-eight patients had LN metastases (35 [73 %] diagnosed by FNA) and twenty seven patients had BM (16 [60 %] diagnosed by FNA). P value was determined comparing primary breast with BM and LN for ER, PR and HER2. ER p values when compared for primary breast with BM and LN were 0.45 and 0.57 respectively, and for PR were 0.31 and 0.06 and for HER2 were 0.45 and 0.07. All three predictive markers are similar in the primary and two metastatic sites (lymph node, bloodspread). Only in primary versus lymph node metastases is there a tendency for PR and HER2 (P values 0.06, 0.07) to be different. For HER2, the majority of lymph node metastases are in cell blocks (FNA), fixed in ethanol rather than formalin, which may have caused false positive HER2 expression.