[182] Impact of Decalcification on Receptor Status in Breast Cancer

F Darvishian, B Singh, S Krauter, L Chiriboga, J Melamed. NYU-Langone Medical Center, New York, NY

Background: Metastasis of breast cancer to bone is observed in up to 70% of patients at post-mortem examination. Bone metastases in breast cancer, especially when solitary, may be amenable to surgical excision and radioablation in addition to systemic therapy. The pathology material obtained from bone specimens requires decalcification. The decalcification process may potentially affect the receptor status of the metastatic breast cancer and, therefore, impact the decision for systemic therapy. We conducted this pilot study to assess the reliability of receptor studies after decalcification.
Design: We prospectively selected 10 random cases of breast excision for cancer. In addition to the regularly proccessed tumor sections, one tumor section was subjected to 1 hour of decalcification following formalin fixation. Immunohistochemical studies for estrogen receptor (ER), progesterone receptor (PR) and her2 were performed on one representative section of the regularly processed tumor block and one decalcified tumor block. Three pathologists (FD, BS, JM) independently scored the slides. Scoring of ER and PR were performed according to the Allred scoring system (proportion 0-5 plus intensity 0-3 with a score range of 0, 2-8). Scoring of her2 was performed according to the Dako scoring system (0-3). The mean scores were used for comparison.
Results: The tumors were all invasive ductal carcinomas except case 3, which was an invasive lobular carcinoma (mean size = 1.8 cm). Six tumors were poorly differentiated and 4 were moderately differentiated. In all cases, the scores either dropped or remained unchanged after decalcification.

Receptor scoring
CaseER score dropPR score dropher2 score droppTpNReceptor status
111021HR+/her2-
22001c1HR+/her2-
32111c1HR+/her2-
431021HR+/her2-
513021HR+/her2-
60001b0her2+
70011c0her2+
82401c1TN
90001c0TN
1000022TN
ER: Estrogen receptor; PR: Progesterone receptor; HR: Hormone receptor; TN: Triple negative

The mean drop in the proportion of tumor cells staining was 21% for ER and 9.8% for PR. The mean drop in the intensity of staining in tumor cells was 1.4 for ER and 1.3 for PR. The mean drop in Allred scoring was 1.8 for ER and 2.0 for PR. The mean score drop for her2 was 1.0.
Conclusions: The immunohistochemical staining for ER, PR and her2 was more heterogeneous after decalcification with an overall reduction in the proportion and the intensity of staining.
Category: Breast

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 20, Tuesday Afternoon

 

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