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Microsatellite Instability Testing for Lynch Syndrome in Colorectal Adenomas
Author(s) -
Anderson Blaire,
Javanbahkt Ayda,
Green Donald,
Godwin Kelly,
Tsongalis Gregory,
Tafe Laura,
Ren Bing
Publication year - 2022
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2022.36.s1.r2661
Subject(s) - microsatellite instability , lynch syndrome , mlh1 , germline mutation , colorectal cancer , medicine , dna mismatch repair , oncology , genetic testing , pms2 , cancer , germline , cancer research , mutation , microsatellite , genetics , biology , gene , allele
Background Patients with Lynch Syndrome (LS), a hereditary condition linked to increased risk of colorectal cancer (CRC) and a variety of other cancers, carry at least one germline variant in a DNA mismatch repair protein (MMR) gene, which results in microsatellite instability (MSI). Screening for MMR/MSI status in CRCs helps identify patients with LS, which is imperative for treatment and surveillance. MSI high instability (MSI‐H) status has been detected in some colorectal adenomatous polyps (CRAs). If MSI‐H can be detected in CRAs from LS patients, this could aid in the prevention of cancer development and facilitate early surveillance. Currently, MMR/MSI testing in CRAs is not used to identify cases of LS. Here we analyze a set of CRAs to assess the utility of using MSI testing to identify patients with LS. Design After completing a retrospective review of our pathology database, we selected 54 CRAs (including tubular, villous, and tubulovillous CRAs) from 32 patients with a history of LS, 21 CRAs from 14 patients with history of sporadic CRC with BRAF mutation or MLH1 promotor methylation, and 38 CRAs from 34 patients who underwent screening colonoscopy. Results from previous molecular testing confirmed germline mutations in the LS group and BRAF mutations or MLH1 promotor methylation in the sporadic CRC group. FFPE tissue was analyzed for MSI status using the Idylla MSI assay (Biocartis, Belgium). Patient demographics and clinical characteristics, pathologic features CRAs, and MSI results were analyzed. Results Frequency of MSI‐H CRA was significantly higher in the LS group (18.5%, [10/54]) than in the sporadic CRC (4.8%, [1/21]) and screening colonoscopy (0/38) groups. CRAs analyzed included 106 tubular CRAs, 2 villous CRAs and 5 tubulovillous CRAs. The MSI‐H CRAs in the LS group included 9 tubular CRAs and one villous CRA. One MSI‐H tubular CRA was identified in the sporadic CRC group. All CRAs from the screening colonoscopy group were MSI stable. Mean ages in years for patients in each study group were 56.9 in the LS group, 79.2 in the sporadic CRC group, and 60.6 in the screening colonoscopy group. Conclusion MSI‐H status is detectable in CRAs from patients with LS. MSI‐H CRAs are more frequently detected in patients with LS than non‐LS patients. These findings demonstrate the utility of MSI testing in CRAs. This can help to identify LS at a pre‐malignant stage, which prevents cancer development and facilitates early surveillance.