Department of Surgery, The University of Auckland, Auckland, New Zealand.
Department of General Surgery, Whangārei Hospital, Te Tai Tokerau, Whangārei, New Zealand; Department of Surgery, The University of Auckland, Auckland, New Zealand.
N Z Med J. 2024 Aug 2;137(1600):31-39. doi: 10.26635/6965.6551.
Lynch syndrome (LS) is estimated to affect 1-3.9% of patients with colorectal cancer (CRC). Testing for LS is important in determining management and establishing surveillance for "Lynch families". Previous studies have identified poor rates of testing for LS in CRC patients. This study aimed to describe adherence to guidelines for testing of newly diagnosed CRC for LS.
A single institution cohort study of patients over 18 years with colorectal adenocarcinoma from 2018-2022 in Te Tai Tokerau, Aotearoa New Zealand was conducted. Rates of baseline immunohistochemistry (IHC) testing for mismatch repair (MMR) deficiency, further testing for MLH1-deficient cases and rates of germline mutational analysis were audited to determine adherence to national guidelines. The rate of LS in newly diagnosed CRC was estimated.
Six hundred and sixty patients were eligible for universal testing for LS, of which 84% (n=553) completed initial IHC testing. MMR deficiency was reported in 20% (n=114) cases. Eighty-nine percent (n=101) was attributable to MLH1 deficiency, of which 99% (n=100) were appropriately tested for BRAF-V600E mutation. Sixty-four percent (4/11) patients indicated for hypermethylation testing were appropriately tested. Seventeen patients had an indication for germline mutational analysis, of which only 29% (n=5) were tested. The estimated incidence of LS in newly diagnosed CRC was 0.7-3.8%.
Compliance with initial IHC testing was good. However, there is a need to improve rates of confirmation genetic testing. The incidence of confirmed LS in this study is 0.7%, however this may be as high as 3.9%.
林奇综合征（LS）估计影响 1-3.9%的结直肠癌（CRC）患者。LS 的检测对于确定管理方案和建立“林奇家族”的监测非常重要。先前的研究已经确定 CRC 患者 LS 检测率较低。本研究旨在描述新诊断 CRC 进行 LS 检测的指南遵循情况。
对 2018 年至 2022 年在新西兰泰泰托科地区年龄在 18 岁以上的结直肠腺癌患者进行了一项单机构队列研究。对 MMR 缺陷的基线免疫组化（IHC）检测、进一步对 MLH1 缺陷病例的检测和种系突变分析的检测率进行审核，以确定是否符合国家指南。估计新诊断 CRC 的 LS 发生率。
共有 660 名患者符合 LS 的普遍检测标准，其中 84%（n=553）完成了初始 IHC 检测。20%（n=114）的病例报告存在 MMR 缺陷。89%（n=101）归因于 MLH1 缺陷，其中 99%（n=100）的病例均适当进行了 BRAF-V600E 突变检测。64%（n=4）需要进行高甲基化检测的患者也进行了适当的检测。17 名患者有进行种系突变分析的指征，但仅有 29%（n=5）进行了检测。新诊断 CRC 的 LS 发生率估计为 0.7-3.8%。
初始 IHC 检测的依从性良好。然而，需要提高确认性遗传检测的比例。本研究中确诊 LS 的发生率为 0.7%，但也可能高达 3.9%。
