[232] A Comparison of HER 2 Expression in Primary Breast Carcinomas vs Organs of Metastasis A Comprehensive Retrospective Review

DF Jones, DJ Dabbs, MQ Rosenzweig, M Chivukula. Magee Womens Hospital of UPMC, Pittsburgh, PA

Background: HER2 overexpression is seen in up to 18% of primary breast carcinomas. Data on the conservation of HER2 status specifically in distant metastases is limited. Our aim is to examine the patterns of HER2 staining in distant metastases as compared to the primary tumor and to determine if differences exist between sites of metastases.
Design: Cases were selected from our electronic archives of 2000-09 using 3 criteria: (1) confirmed metastasis (met) from a breast primary, (2) exclusion of loco-regional mets, and (3) HER2 analysis on both the primary and met. Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) results originally on record were used. Metastatic site groups (bone, serosa-associated sites, solid organ, and non-locoregional lymph nodes) were compared.
Results: 156 cases were identified with HER2 analysis on both the primary and met. IHC was done on 150 (96%) of the primary tumors and 145 (93%) of the mets. FISH was done on 38 (24%) and 47 (30%) of the primary and mets, respectively. In 68 specimens, either primary or met, both IHC and FISH were done. We found a discrepancy between the IHC and FISH in 3 (4%). HER2 was amplified in 52 (33%) and 51 (33%) of the 156 primary tumors and mets, respectively (95% CI 26-42% for both). Ignoring borderline results, 146 cases had HER2 results on both the primary and met. Concordance in HER2 overexpression between primary and met was 82% (95% CI 75-88%) overall, in bone 79%, solid organs 86%, serosa-associated sites 83%, and lymph nodes 64%.

Primary Tumor HER2 (-)
Metastatic SiteHER2 (+)HER2 (-)
Bone519
Solid Organ641
Serosa115
Lymph Node18




Primary Tumor HER2 (+)
Metastatic SiteHER2 (+)HER2 (-)
Bone41
Solid Organ285
Serosa43
Lymph Node14


Results for met sites are summarized in Tables 1&2. There was no statistically significant difference in the HER2 positive proportion between primary and met either for all cases taken together (p=1.00) or for met sites separately (bone p=0.22, solid organ p=0.63, serosa p=1.00, lymph node p=0.37). Additionally, pairwise comparisons between met sites did not reveal statistically significant differences in HER2 overexpression (data not shown).
Conclusions: HER2 overexpression is preserved in distant metastases of breast cancer, which may have implications in its treatment. Additionally, HER2 overexpression does not correlate with metastasis to any particular site.
Category: Breast

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 21, Monday Morning

 

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