Markers of Metastatic Breast Cancer: Correlations between GCDFP-15 or Mammaglobin Expression and Tumor Grade, Hormone Receptor, and HER2 Expression
AM Gown, LC Goldstein, PL Kandalaft, HC Hwang, SJ Kussick, CC Tse. PhenoPath Laboratories, Seattle, WA; IMPRIS, Seattle, WA
Background: Both the gross cystic disease fluid protein-15 (GCDFP-15) and mammaglobin represent excellent markers of carcinomas of breast origin that can be applied in the analysis of carcinomas presenting at metastatic sites, showing sensitivities of nearly 80% and 60%, respectively, with a combined sensitivity of almost 90%. However, there are few published studies examining the relationship of expression of these breast-restricted markers with breast cancer grade and expression of the biomarkers ER, PR, and HER2, which could have important implications in their use in certain clinicopathologic settings.
Design: A series of 334 breast cancers were tested on whole tissue sections for expression of GCDFP-15 (Leica/Novocastra, clone 23A3) mammaglobin (Zeta Corp, clone 31A5), estrogen receptor (Thermofisher, SP1), progesterone receptor (Dako PgR636), and HER2 (Thermofisher, SP3). Scoring was based on percentage of positive tumor cells: negative (0%), rare cells (<1%), focal (1-25%), variable (26-75%), uniform (>75%) except for HER2, which was scored as positive, negative, or equivocal. Tumors were graded using a modified Nottingham score (1 through 3). Chi-square and other statistical analyses were performed to determine the expression relationships among the different markers.
Results: As expected, there was a strong inverse correlation found between HER2 and ER expression (p< 0.0001), but also a strong positive correlation between GCDFP-15 and mammaglobin expression (p<0.0001). Statistically significant positive correlations were found between ER expression and expression of GCDFP-15 (p=0.007) and mammaglobin (p=0.012), but no relationship was found between expression of either of the breast-restricted markers and HER2 expression (p=0.10, GCDFP-15; p=.81, mammaglobin). Strong inverse correlations were found between Nottingham grade and both GCDFP-15 (p<0.0001) and mammaglobin expression (p=0.006).
Conclusions: While GCDFP-15 and mammaglobin are excellent markers of carcinomas of breast origin presenting at metastatic sites, caution should be used in their use in the context of high grade, ER-negative cancers given the strong correlations found between these biomakers and expression of both GCDFP-15 and mammaglobin.
Monday, March 22, 2010 1:00 PM
Poster Session II # 47, Monday Afternoon