Assessment of HER2 gene amplification in breast cancer: a comparison of dual-color in-situ hybridization and fluorescence in-situ hybridization / 中华病理学杂志

ABSTRACT

<p><b>OBJECTIVE</b>To compare dual-color in-situ hybridization (DISH) with fluorescence in situ hybridization(FISH) in evaluating the human HER2 gene status in invasive breast cancer.</p><p><b>METHODS</b>HER2 gene status in 110 cases of breast invasive ductal carcinomas with a 2+ score on immunohistochemistry (IHC) was investigated by FISH and DISH. The 2007 and 2013 ASCO (American Society of Clinical Oncology)/CAP (College of American Pathologists) HER2 guideline were used respectively to evaluate the agreement between these two techniques.</p><p><b>RESULTS</b>(1) Using the 2007 ASCO/CAP guideline, the overall concordance between FISH and DISH was 97.3% (107/110). Fifty of 51 samples with amplification by FISH were also detected by DISH and the remaining one sample was equivocal.Eight of 10 equivocal samples by FISH were equivocal by DISH and the remaining two samples were negative. Forty-nine samples with no amplification by FISH were all negative by DISH. The concordance was 98.0%, 8/10 and 100.0% respectively for the FISH positive, equivocal and negative groups. (2) Using the 2013 ASCO/CAP guideline, the overall concordance between FISH and DISH was 90.0% (99/110). Fifty-three of 55 samples with amplification by FISH were also detected by DISH and the remaining two were equivocal and negative respectively. Two of 12 equivocal samples by FISH were equivocal by DISH and the remaining ten samples were negative in 7 cases and equivocal in 3 cases. Forty-three samples with no amplification by FISH were all negative by DISH. The concordance was 96.4%, 3/12 and 100.0% respectively for the FISH positive, equivocal and negative groups. Pearson correlation analysis indicated that the HER2 status detected by FISH and DISH were significantly correlated with each other (R=0.584, P<0.01).</p><p><b>CONCLUSIONS</b>There is a high concordance between DISH and FISH for assessing the HER2 gene status in invasive breast cancer. DISH is a new option for assessing HER2 gene status of breast cancer in clinical practice. The clinical significance of the discordance between DISH and FISH in equivocal cases warrants further study.</p>