Kluvers Katla R, Tryggvason Thordur, Stefansdottir Vigdis, Jonasson Jon G, Snaebjornsson Petur, Haraldsdottir Sigurdis
University of Iceland, Faculty of Medicine, Reykjavik, Iceland.
Department of Pathology, Landspitali University Hospital of Iceland, Reykjavik, Iceland.
Acta Oncol. 2025 Jan 31;64:188-190. doi: 10.2340/1651-226X.2025.41957.
Screening for Lynch syndrome (LS) with mismatch repair (MMR) protein immunohistochemistry (IHC) in all patients with newly diagnosed colorectal (CRC) and endometrial cancer (EC) was implemented in Iceland in 2017. The aim of the study is to assess the accuracy of screening in 2020-2022 and compare it to 2017-2019 when screening was initiated.
PATIENTS/MATERIALS AND METHODS: All patients diagnosed with CRC and EC according to the Icelandic Cancer Registry in 2020-2022 were included. Screening results were crossmatched with a genotyping database from deCODE to calculate sensitivity and specificity for LS detection. Results: In 2020-2022, 429 of 522 (82%) diagnosed CRCs were stained and 90 of 106 (85%) ECs, compared to 74% of CRCs and 82% of ECs in 2017-2019. The screening protocol was followed in 90% of cases for CRCs and 95% of cases for ECs compared to 89% and 68% during 2017-2019. The sensitivity of IHC as a screening method for LS was 70% and specificity 88% with a positive and negative predictive value of 8.4% and 99.4%, respectively.
Three LS cases were missed with MMR IHC (1 MSH6 and 2 PMS2 carriers), it is possible these patients had sporadic cancers unrelated to their LS carrier status. MSH6 and PMS2 deficiency strongly predicts LS in Iceland.
冰岛于2017年对所有新诊断的结直肠癌（CRC）和子宫内膜癌（EC）患者采用错配修复（MMR）蛋白免疫组化（IHC）进行林奇综合征（LS）筛查。本研究旨在评估2020 - 2022年筛查的准确性，并将其与2017 - 2019年筛查启动时进行比较。
患者/材料与方法：纳入了2020 - 2022年根据冰岛癌症登记处诊断为CRC和EC的所有患者。将筛查结果与来自deCODE的基因分型数据库进行交叉匹配，以计算LS检测的敏感性和特异性。结果：在2020 - 2022年，522例诊断为CRC的患者中有429例（82%）进行了染色，106例EC患者中有90例（85%）进行了染色，而2017 - 2019年CRC患者的染色比例为74%，EC患者为82%。CRC患者90%的病例和EC患者95%的病例遵循了筛查方案，而2017 - 2019年期间这一比例分别为89%和68%。IHC作为LS筛查方法的敏感性为70%，特异性为88%，阳性预测值和阴性预测值分别为8.4%和99.4%。
MMR IHC漏检了3例LS病例（1例MSH6携带者和2例PMS2携带者），这些患者可能患有与其LS携带者状态无关的散发性癌症。在冰岛，MSH6和PMS2缺陷强烈提示LS。
