[150] Predictive Markers (ER, PR, HER2, HER2FISH) Pre- and Post-Neoadjuvant Chemotherapy in Primary Breast Carcinoma

MD Darrow, C Cohen, A Nassar. Emory University, Atlanta, GA; The Mayo Clinic, Rochester, MN

Background: The estrogen receptor (ER), progesterone receptor (PR), and HER2 profile of a female primary breast carcinoma plays a significant role as a predictive marker in patient management and treatment. Because of the increasing utilization of neoadjuvant chemotherapy or hormone therapy, surgically resected carcinomas often show marked treatment effect. The aim of this study was to compare immunohistochemical (IHC) profiles (ER, PR, HER2, HER2 FISH) of primary breast carcinomas before and after neoadjuvant chemotherapy to assess the effects of these treatment modalities on hormone receptor status.
Design: Primary breast carcinomas from 55 female patients treated with neoadjuvant therapy after needle core biopsy or fine needle aspiration diagnosis between 2004-2008 were included. Histologic data was collected for each case, including site, type, grade, tumor size (cm), pre- and post- neoadjuvant treatment IHC panel (ER, PR, HER2), and fluorescence in-situ hybridization (FISH) for HER2. Clinical information (stage, treatment type, and lymph node status) was obtained. Exclusion criteria included patients not treated with neoadjuvant chemotherapy or cases with incomplete IHC data, resulting in a final sample size of 38.
Results: Of the 38 carcinomas studied, 53% were grade III, 92% were of ductal type, and 58% had metastasized to axillary lymph nodes. The mean size of carcinomas was 3.9 cm (range 0.1- 12 cm). Forty-five percent were positive for ER by IHC both pre- and post- neoadjuvant treatment (P=1.00). IHC studies for PR in these 38 patients showed 37% positivity for PR pre-neoadjuvant therapy and 21% positivity post-treatment, with a statistically significant P value of 0.03. For 37 patients with HER2 IHC, 32% were positive pre-treatment, and 22% were positive post-treatment (P = 0.20). For 7 patients, HER2 FISH was positive in 71% pre-therapy and in 57% post-treatment (P=0.32). Overall concordance ranged from 73.0-89.5%.
Conclusions: Profiles for ER, HER2 IHC, and HER2 FISH were not significantly different in primary breast carcinomas before and after neoadjuvant chemotherapy. There was a statistically significant decrease in PR positivity post-treatment. Further investigation is warranted to assess reproducibility of technique and investigate clinical implications of loss of PR status in treated patients.
Category: Breast

Monday, March 9, 2009 9:30 AM

Poster Session I Stowell-Orbison/Autopsy Award # 26, Monday Morning