No abstract

overall MMR status when age 50 was used as a hypothetical testing threshold. After correcting for tumour grade as a confounding variable it was shown that MLH1 and PMS2 expression were negatively correlated with increasing age while MSH6 expression was positively correlated with increasing age at diagnosis (figures 1 and 2). Conclusion There is no statistically significant difference in overall immunohistochemical MMR status when using the age of 50 as a threshold for tumour analysis. Such a threshold would have missed 82.3% of cases with tumoral MMR deficiency and should not be included in lab protocols for EEC IHC analysis. Reflex testing of all EEC cases is highly advised as IHC testing is no longer solely about diagnosis of Lynch syndrome. Prospective evidence is required to clarify the role IHC scoring and semi-quantitative analysis should play in MMR status interpretation and patient management especially in the ever-evolving field of targeted therapeutics. Disclosures This study was self-financed. Authors declare they have no conflict of interest, financial or otherwise.