[1961] Evaluation of ER, PR and Her2 in Breast Carcinoma Metastatic to Bone: A Comparison of Results between FNA Cell Blocks and Surgical Biopsies

Gitika Aggarwal, Joanna Magda, Maria E Arcila, Oscar Lin, Marcia Edelweiss. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Immunohistochemical profile (IHC) is critical in the management of patients with metastatic breast carcinoma. Accurate detection of ER, PR and Her2 require strict adherence to ASCO/CAP guidelines. The decalcification process (decal) performed in surgical biopsies (SB) of bone metastasis (bmets) has the potential to cause IHC alterations and delayed reporting. Cell blocks (CB) obtained from FNA of bmets represent a viable alternative. In the present study we aimed to compare ER, PR and Her2 IHC results on formalin-fixed CB to those on concurrent formalin-fixed decalcified SB.
Design: Thirty nine archival FNA samples with concurrent SB from patients with bmets were identified over a period of 12 months. Tumor cells were present in 31/39 CB (80%) of which 22/31 (71%) had more than 20 tumor cells. Archival blocks or IHC stains were available in 27 CB/SB pairs. IHC for ER, PR, and Her2 were performed/evaluated on these 27 CB and compared to those of the paired SB. Interpretation of ER and PR IHC included intensity of nuclear staining (weak, moderate, strong), and % of stained tumor cells. Her2 IHC scoring, was evaluated for complete membranous staining, uniformity (present or absent) and intensity of staining pattern. This semiquantitative scoring system was used for both CB and SB.
Results: Discrepant IHC was found in 4/27 cases in which the CB showed cells positive for ER (ranging from 5-98% of the cells) while no ER staining was seen in the matching SB (p=0.29). Interestingly, crush artifact was noted in 3 of these 4 SB cases. ER was originally positive in the primary breast carcinoma in 3 of such cases, while negative in 1. Seven (35%) of the remaining 20 ER positive SB cases showed a lower % of ER positive tumor cells (> 30% difference), as well as, decreased intensity of staining when compared to CB. Overall, comparison of ER staining (including number of discordant cases, decrease in intensity and % of stained tumor cells in SB) showed significant difference of results between CB and SB (p =0.0002). PR and Her2 comparison between CB and SB did not yield significant results.

Summary of IHC results on 27 paired CB and SB
 CBSBDiscordant IHCp value
Her2 (3+)220>0.5
Her2 (2+)523>0.5
Her2 (0/1+)20233>0.5

Conclusions: Formalin-fixed CB that are adequately cellular represent a better platform for IHC studies in patients with metastatic breast cancer to bone when compared to SB. The decal and crush artifact in SB can lead to delayed reporting and less accurate IHC results.
Category: Quality Assurance

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 273, Tuesday Morning


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