Assessing the HER2 status in mucinous epithelial ovarian cancer on the basis of the 2013 ASCO/CAP guideline update.

Her2 gene amplification and protein overexpression are important factors in predicting clinical sensitivity to anti-HER2 monoclonal antibody therapy in breast, gastric, or gastro-esophageal junction cancer patients. The purpose of this study was to evaluate the HER2 status in the mucinous epithelial ovarian cancer (EOC). Adopting the 2013 American Society for Clinical Oncology and the College of American Pathologists guideline update for HER2 testing, 49 tissue microarray samples of mucinous EOC were analyzed by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) tests. The prevalence of HER2 positivity in Asian mucinous EOC was 9 of 49 Asian women (18.37%). The overall concordance was 100% between IHC and FISH results. Her2 gene copies before chromosome-17 correction increased significantly in a stepwise order through the negative, equivocal, and positive IHC result categories (P<0.001), as did the Her2 gene copies after chromosome-17 correction (P<0.001). Of the Taiwanese cohort (n=21), HER2 heterogeneity was 4.76% (1/21) in all but 14.26% (1/7) in HER2-positive cancer. In conclusion, we demonstrated that the prevalence of HER2 positivity in both Asian and white women was comparable; complete HER2 concordance existed between IHC and FISH tests for the Her2 gene copies per tumor cell either before or after correction of chromosome-17, and this can be applied as a potentially valuable tool to analyze the HER2 status. Polysomy-17 was absent under the CEP17 cutoff ≥3. The existence of HER2 heterogeneity can be discerned in certain HER2-expressed primary mucinous EOC in Taiwanese women.