Understanding HER2 testing in gynecological cancers

This video from Prof. Fernando Soares provides a practical, guideline-driven overview of HER2 immunohistochemistry (IHC) testing and scoring in endometrial, cervical, and ovarian cancers, detailing why accurate assessment is now critical for treatment selection.  

Key highlights include: 

• When and why to test HER2 in gynecological cancers 
• Practical guidance on HER2 IHC testing and treatment-based scoring  
• Tumour-specific treatment implications according to HER2 status 
• Review of HER2-targeted therapies 

Clinical takeaways

• HER2 IHC testing is recommended in p53-aberrant endometrial cancer (EC), advanced or recurrent cervical cancer, and recurrent ovarian cancer, as HER2 status guides treatment selection. HER2 assessment and reporting should follow the CAP gynecologic reporting template
• In EC, patients with HER2+ uterine serous carcinoma are eligible for 1st-line carboplatin–paclitaxel + trastuzumab. In this setting, HER2 positivity is defined as IHC 3+ (strong complete or basolateral/lateral membranous staining in >30% of tumour cells [TC]) or IHC 2+ (strong staining in ≤30% of TC, or weak-to-moderate staining in ≥10% of TC) with ISH+
• In the recurrent or metastatic setting across endometrial, cervical, and ovarian cancers, patients with HER2-positive disease are eligible for ≥2nd-line treatment with T-DXd in certain circumstances. Here, HER2 positivity is defined as IHC 3+ (strong complete or basolateral/lateral staining in ≥10% of TC) or IHC 2+ (weak-to-moderate complete or basolateral/lateral staining in ≥10% of TC)
• Standardisation across pre-analytic, analytic, and post-analytic phases is essential for reliable HER2 interpretation. In the absence of gynecological-specific guidance, established ASCO/CAP breast cancer standards can be applied