Results of morphological screening for Lynch syndrome during the period 2013-2016.

The introduction of a screening system for Lynch syndrome in pathology laboratories in Plzen yielded 24 diagnoses of Lynch syndrome during the period of 2013-2016, 20 of them presenting with colorectal cancer. In 8 of those 24 cases germline mutations of MMR genes, previously not recognized as pathogenic with certainty, were detected. Although the frequency of Lynch syndrome in patients with colorectal cancer was only 0.34 % in total, following introduction of the universal immunohistochemical investigation of MMR (mismatch repair) proteins expression in all colorectal cancers examined in Sikl´s Institute of Pathology the frequency per year in this department reached 2.4 %. The results favor universal immunohistochemical screening for Lynch syndrome in colorectal and endometrial cancer cases over a selective approach based on a combination of clinical and morphological criteria. Increased effectiveness of the universal approach is not brought about only by higher sensitivity of the immunohistochemical examination per se, but also by the possibility of automation of the process leading to increased adherence even of pathologists not directly engaged in Lynch syndrome management. However, the introduction of a nation-wide universal screening system requires support from the government and health insurance companies. Keywords: colorectal cancer - endometrial cancer - immunohistochemistry - Lynch syndrome - MMR - screening.