• HER2
• ovarian cancer
• IHC
• FISH
• biomarker
• ovarian tumour
• immunohistochemistry
• gynaecological pathology
• breast cancer
• tumour markers
• colorectal cancer
• proteins
• molecular pathology

We read with interest the recent article by Yan et al,1 in which a small cohort (n=85) of ovarian tumours were assessed for HER2 amplification by immunohistochemistry (IHC), fluorescence in situ hybridisation (FISH) and chromogenic in situ hybridisation. HER2 amplification and protein overexpression were identified in 35.3% (6/17) and 29.4% (5/17) of primary mucinous carcinomas, respectively, with none of the other histological subtypes demonstrating HER2 amplification or overexpression. In another recent study, Tan et al.2 used array-based comparative genomic hybridisation to establish the genomic profiles and regions of recurrent copy number change in 50 pure ovarian clear cell carcinomas (OCCCs). In that study, 7/50 (14%) OCCCs were found to harbour HER2 gene amplification and protein overexpression, representing <2% of the ovarian cancer population as a whole. The authors in both studies quite rightly conclude that HER2 may therefore be a potential therapeutic target in non-serous ovarian tumours. However, since there is documented evidence of HER2 overexpression in other histological subtypes of ovarian cancer, including serous carcinomas3–5 and some HER2-directed therapies (such as pertuzumab), may be effective against tumours which express non-amplified levels of the receptor,6 we sought to better define the frequency, quantity and distribution of HER2 expression …