Molecular Difference between Pure Invasive Ductal Carcinoma (IDC) and the IDC Components of the Tumors with Co-Existing Ductal Carcinoma In Situ
Jiping Da, Jianmin Wang, Huijiao Chen, Bing Wei, David G Hicks, Ping Tang. University of Rochester Medical Center, Rochester, NY; RTI Health Solution, Research Triangle Park, NC
Background: Although invasive ductal carcinoma (IDC) is frequently associated with co-exisitng ductal carcinoma in situ (DCIS), we often observed IDC presence without a DCIS component. Are these “pure” IDC molecularly similar to the IDC component with co-existing DCIS? Here we sought to compare a panel of biomarker expression to investigate if there are distinquishing molecular differences between these two groups.
Design: We identified 118 cases of pure IDC between 1997 and 2008 from our departmental file; along with 380 IDC with co-existing DCIS. Tissue microarrays (TMAs) were constructed for each group. Immunohistochemical (IHC) analyses were performed on these TMAs for ER, PR, HER2, Ki-67, EGFR, CK5/6, C35, IMP3, AR and p53. ER, PR and AR were recorded as Allred scores (3 and greater as positive); HER2 was scored as CAP 2007 guidelines (>30% of tumor cells with 3+ membrane staining as positive); Ki-67 was scored as positive with >15% of nuclear staining; EGFR was designated as positive if any tumor cells showed 1+ positive stain; a strong cytoplasmic stain was considered as positive for CK5/6, C35 and IMP3; and >10% strong cytoplasmic stain was considered as positive for p53.
Results: Among the cases we were able to obtain IHC data for above molecules; we compared their IHC expression patterns between pure IDC and the IDC component with co-existing IDC. We found that 1) the only molecule with significant different expression pattern between these two groups was CK5/6 (22% in pure IDC vs. 10% in IDC component, p=0.0019), which might due to the higher rate of triple tumors (16.1% vs. 9.7% in IDC component) in pure IDC group; 2) although no significant difference was noted, there were trend of expression difference with HER2 over-expression (2% in pure IDC and 7% in IDC component. P=0.0757); Ki-67 (25% in pure IDC vs. 16% in IDC component, p=0.069); C35 (45% in pure IDC vs. 56% in IDC component, p=0.0752) and p53 (55% in IDC vs. 66% in IDC component, p=0.0747); 3) no significant difference were noted with ER, PR, EGFR, IMP3 and AR between these two groups.
Conclusions: “Pure” IDC and the IDC component with co-existing DCIS share largely similar molecular alteration. Further studies are needed to investigate the molecular, biological and clinical difference between the two groups of the tumors.
Tuesday, March 20, 2012 9:30 AM
Poster Session III # 33, Tuesday Morning