"HER2 immunohistochemistry inter-observer reproducibility in 205 cases of invasive breast carcinoma additionally tested by ISH" Answer to the statistical issue to avoid misinterpretation.

Assessment of HER2 biomarker in invasive breast carcinoma patients allows a specific therapeutic approach. Clinical guidelines indicate immunohistochemistry (IHC) and in situ hybridization (ISH) to test HER2, however both have drawbacks which results in low reproducibility of results especially in equivocal cases. Our main objective is to quantify inter-observer IHC reproducibility and cross it with the ISH result.