[171] Immunohistochemical Profile of Breast Cancer with Respect to ER and HER2 Status

Nika C Gloyeske, Jing Yu, Esther Elishaev, Anna H Woodard, David J Dabbs, Rohit Bhargava. Magee-Womens Hospital of University of Pittsburgh Medical Center, Pittsburgh, PA

Background: Immunohistochemical (IHC) stains are performed to confirm the identity of breast cancer when it metastasizes or presents as a tumor of unknown primary. There are very few studies that have evaluated a panel of stains on a single large dataset, which is required for direct comparison between different antibodies. Moreover, almost no data exists on IHC profiles of breast cancer with respect to receptor expression.
Design: A panel of IHC stains was performed on tissue microarrays of 198 primary breast carcinomas with 3 fold redundancy. The panel was chosen to include breast specific markers and markers that are expressed in tumors resembling breast. It included CK7, CK20, PAX8, vimentin, GCDFP-15, mammaglobin, NYBR1, and androgen receptor. ER, PR and HER2 results were available from pathology reports.
Results: The individual marker positivity was 92% (172/186) for CK7, 80% (151/189) for AR, 55% (105/190) for NYBR1, 52% (99/189) for mammaglobin, 31% (59/191) for vimentin, 12% (22/195) for GCDFP-15, 0.5% (1/186) for CK20, and 0% (0/188) for PAX8. Data for all markers was available on 178 carcinomas that resulted in a total of 41 profiles. The most common tumor profiles are summarized for each IHC/molecular class of breast cancer below.
Profiles of ER+/HER2- Tumors
CK7+/CK20-/PAX8-/Vim-/GCD-/MGB+/NYBR1+/AR+/PR+ (17/125)
CK7+/CK20-/PAX8-/Vim-/GCD-/MGB-/NYBR1+/AR+/PR+ (15/125)
CK7+/CK20-/PAX8-/Vim-/GCD-/MGB+/NYBR1-/AR+/PR+ (11/125)
Profiles of ER+/HER2+ Tumors
CK7+/CK20-/PAX8-/Vim-/GCD-/MGB+/NYBR1-/AR+/PR+ (3/17)
CK7+/CK20-/PAX8-/Vim-/GCD+/MGB+/NYBR1+/AR+/PR+ (2/17)
CK7+/CK20-/PAX8-/Vim-/GCD-/MGB-/NYBR1+/AR+/PR+ (2/17)
Profiles of ER-/HER2+ Tumors
No consistent profile in 7 tumors but all CK7+, CK20-, PAX8-, PR-
Profiles of ER-/HER2- Tumors
CK7+/CK20-/PAX8-/Vim+/GCD-/MGB-/NYBR1-/AR-/PR- (15/29)
CK7+/CK20-/PAX8-/Vim+/GCD-/MGB-/NYBR1+/AR-/PR- (2/29)
CK7+/CK20-/PAX8-/Vim+/GCD-/MGB+/NYBR1-/AR-/PR- (2/29)
Conclusions: Although the majority of breast carcinomas are CK7+/CK20-, an unusual profile (i.e. CK7-/CK20-) seen in ∼8% cases can create confusion in investigation of a tumor of unknown primary. Fortunately, most of the CK7 negative tumors are ER positive. Vimentin expression in triple negative breast cancer can create confusion in distinction from high grade endometrioid endometrial carcinoma and therefore PAX8 should always be included in this differential diagnosis. The results of this study define the sensitivity of antibodies against each other and strongly support the use of immunohistochemical panels when investigating tumors of unknown primary.
Category: Breast

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 17, Wednesday Morning


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