Impact of polysomy 17 on Her-2/neu immunohistochemistry in breast carcinomas without Her-2/neu gene amplification Journal Article
| Authors: | Lal, P.; Salazar, P. A.; Ladanyi, M.; Chen, B. |
| Article Title: | Impact of polysomy 17 on Her-2/neu immunohistochemistry in breast carcinomas without Her-2/neu gene amplification |
| Abstract: | Her-2/neu, a proto-oncogene located on chromosome 17, is an important biomarker in breast carcinoma. Immunohistochemistry (IHC) is currently the most widely used method for assessing Her-2/neu status. Some IHC-positive cases do not show Her-2/neu gene amplification by fluorescence in situ hybridization (FISH). It has been suggested that some of these IHC "false positive" results may in part be due to increased copy number of chromosome 17 resulting in increased Her-2/neu protein expression. We analyzed IHC and FISH data from 561 cases of invasive breast carcinoma to test this hypothesis. IHC and FISH for Her-2/neu were performed on formalin-fixed, paraffin-embedded sections of 561 invasive breast carcinomas. The IHC results were interpreted as 0, 1+, 2+, or 3+ according to the manufacturer's recommended criteria. The FISH results were expressed as a ratio of Her-2/neu/chromosome 17 and were interpreted as positive (> = 2.0) or negative (<2.0) for gene amplification according to the manufacturer's recommended scoring system. We found that in IHC 3+/FISH-negative cases (n = 15) both the average chromosome 17 copy number and the average Her-2/neu copy number were significantly higher than that in IHC (0 to 2+)/FISH-negative cases (n = 411) (2.45 vs. 1.68; P < 0.0001, and 3.19 vs. 1.95; P < 0.0001, respectively). In contrast, the IHC 2+/FISH-negative cases did not exhibit a significantly increased number of chromosome 17 compared to IHC 0 to 1+ cases. In addition, the average copy number of chromosome 17 in FISH-positive cases (n = 135) was significantly higher than that in FISH-negative cases (n = 426) (2.27 vs. 1.70; P < 0.0001), indicating a general association of increased chromosome 17 copy number with Her-2/neu gene amplification. Thus, our data suggest that IHC 3+ immunostaining without scorable gene amplification may indeed be, at least in some cases, the result of increased Her-2/neu protein expression secondary to an increased copy number of chromosome 17, associated with an increased total number of Her-2/neu gene copies per tumor cell. |
| Keywords: | immunohistochemistry; controlled study; human tissue; protein expression; major clinical study; disease marker; in situ hybridization, fluorescence; proto oncogene; gene amplification; breast neoplasms; tumor marker; cancer genetics; fluorescence in situ hybridization; cancer cell; breast carcinoma; data analysis; scoring system; diagnostic error; chromosome aberrations; genes, erbb-2; chromosome 17; oncogene neu; chromosomes, human, pair 17; chromosome number; numerical chromosome aberration; humans; human; female; article; polysomy 17 |
| Journal Title: | Journal of Molecular Diagnostics |
| Volume: | 5 |
| Issue: | 3 |
| ISSN: | 1525-1578 |
| Publisher: | Elsevier Science, Inc. |
| Date Published: | 2003-08-01 |
| Start Page: | 155 |
| End Page: | 159 |
| Language: | English |
| PUBMED: | 12876205 |
| PROVIDER: | scopus |
| PMCID: | PMC1907330 |
| DOI: | 10.1016/S1525-1578(10)60467-9 |
| DOI/URL: | |
| Notes: | Export Date: 12 September 2014 -- Source: Scopus |
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