Abstract：
OBJECTIVE: 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.
METHODS: 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.
RESULTS: 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%.
CONCLUSIONS: 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%.
METHODS: 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.
RESULTS: 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%.
CONCLUSIONS: 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%.
摘要：
目的：估计Lynch综合征（LS）影响1-3.9%的结直肠癌（CRC）患者。LS的测试对于确定“林奇家庭”的管理和建立监视非常重要。先前的研究已经确定CRC患者的LS检测率低。这项研究旨在描述对新诊断的CRCLS测试指南的遵守情况。
方法：2018-2022年在TeTaiTokerau进行的18岁以上结直肠腺癌患者的单机构队列研究，新西兰进行了Aotearoa。错配修复（MMR）缺陷的基线免疫组织化学（IHC）检测率，我们对MLH1缺陷病例的进一步检测和种系突变分析率进行了审核,以确定是否遵守国家指南.估计新诊断CRC中LS的发生率。
结果：六百六十位患者有资格进行LS的通用检测，其中84%(n=553)完成了初始IHC检测。据报道，MMR缺乏的病例占20％（n=114）。89%(n=101)归因于MLH1缺乏，其中99%(n=100)进行了适当的BRAF-V600E突变检测。64％（4/11）的超甲基化测试患者进行了适当的测试。17名患者有生殖系突变分析的指征，其中只有29%(n=5)进行了测试。新诊断CRC中LS的估计发生率为0.7-3.8%。
结论：对初始IHC检测的依从性良好。然而,有必要提高基因检测的确认率。本研究中确诊LS的发生率为0.7%，然而，这可能高达3.9%。
方法：2018-2022年在TeTaiTokerau进行的18岁以上结直肠腺癌患者的单机构队列研究，新西兰进行了Aotearoa。错配修复（MMR）缺陷的基线免疫组织化学（IHC）检测率，我们对MLH1缺陷病例的进一步检测和种系突变分析率进行了审核,以确定是否遵守国家指南.估计新诊断CRC中LS的发生率。
结果：六百六十位患者有资格进行LS的通用检测，其中84%(n=553)完成了初始IHC检测。据报道，MMR缺乏的病例占20％（n=114）。89%(n=101)归因于MLH1缺乏，其中99%(n=100)进行了适当的BRAF-V600E突变检测。64％（4/11）的超甲基化测试患者进行了适当的测试。17名患者有生殖系突变分析的指征，其中只有29%(n=5)进行了测试。新诊断CRC中LS的估计发生率为0.7-3.8%。
结论：对初始IHC检测的依从性良好。然而,有必要提高基因检测的确认率。本研究中确诊LS的发生率为0.7%，然而，这可能高达3.9%。
