[135] Hormone Receptor and HER2 Profiles before and after Neoadjuvant Chemotherapy: Experience at Two Centers.

Adriana D Corben, Clare D'Arcy, Rita Abi-Raad, Alessandro Bombonati, Alphonse Taghian, Muzaffar Akram, Frederick C Koerner, John H Eichhorn, Elena F Brachtel. Memorial Sloan-Kettering Cancer Center, New York, NY; Massachusetts General Hospital and Harvard Medical School, Boston

Background: Breast cancer, especially in locally advanced stages, may be treated with neoadjuvant chemotherapy (NACT) to reduce local disease and assess treatment response. Complete pathologic response (pCR) is infrequent, and in most cases a variable amount of residual tumor is present. Current guidelines recommend repeating hormone receptor and HER2 studies on the residual tumor after NACT. We evaluated the hormone receptor and HER2 profiles in a combined cohort of 120 patients who underwent NACT to determine the concordance rate between pre- and post-NACT hormone receptor and HER2 results at our institutions.
Design: One hundred and twenty women with locally advanced breast cancer were selected for this study who underwent diagnosis (pre-NACT core biopsy), NACT and surgery (post-NACT excision or mastestomy) at our centers between 2000 and 2010. Routine immunoperoxidase procedures with antibodies by Dako® and/or Ventana® were followed for estrogen receptor (ER), progesterone (PR), and HER2 proteins. ER and PR were considered positive if >1%, and negative if <1% of tumor cells stained. HER2 expression was scored following guidelines. HER2 FISH was performed on HER-2 (2+) cases with HER2/CEP 17 dual-color probe by Vysis®. Cases were then grouped as ER (+/-) and HER2 (+/-), with HER2+ indicating strong (3+) overexpression of HER2 and/or HER2 amplification by FISH.
Results: Sixteen cases (13%) showed complete pathological response (pCR) at excision, evenly distributed between ER-HER2- (24%), ER-HER2+ (19%), ER+HER2+ (19%), and ER+HER2- (19%). 3 cases (19%) showed ER+ HER2 (2+) with no available HER2-FISH. 68% of residual carcinomas were ER+ before NACT, as were 68% after NACT, although 7 cases changed from ER+ to ER- and 3 from ER- to ER+, reducing the actual concordance to 89%. PR+ cases declined from 65% (pre-NACT) to 59% (post-NACT). HER2 (3+) cases declined from 24% to 17%.
Conclusions: Tumors with pCR are evenly distributed between ER+/HER2+, ER+/HER2-, ER-/HER2+ and ER-/HER- subsets. Most residual invasive carcinomas maintain the pre-NACT ER, PR and HER2 status. The ER profile changed in a proportion of cases (11%) from ER+ to ER-, or ER- to ER+; a slightly decreased PR expression post-NACT may reflect treatment-related changes in hormone receptor expression. Several cases of pCR may have contributed to the decline of HER2 overexpressing tumors post-NACT.
Category: Breast

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 13, Wednesday Morning

 

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