%0 Journal Article
%T Microsatellite instability is highly prevalent in older patients with colorectal cancer.
%A Jakob D
%A Orth V
%A Gödde D
%A Zirngibl H
%A Ambe PC
%J Front Surg
%V 11
%N 0
%D 2024
%M 38601878
%F 2.568
%R 10.3389/fsurg.2024.1288061
%X <B>UNASSIGNED: </B>Clinical guidelines suggest screening of colorectal cancer (CRC) for microsatellite instability (MSI). However, microsatellite instability-high (MSI-H) CRC is not rare in older patients. This study aimed to investigate the prevalence of MSI-H CRC in an unselected population in an age-based manner.<BR><B>UNASSIGNED: </B>A retrospective analysis of data from patients undergoing radical surgery for CRC was performed. Only cases with results from MSI testing using immunochemistry (IHC) were analyzed. Age-based analyses were performed using two cut-off ages: 50 years. as stated in Amsterdam II guidelines, and 60 years. as outlined in the revised Bethesda criteria.<BR><B>UNASSIGNED: </B>The study population included 343 (146 female and 197 male) patients with a median age of 70 years (range 21-90 years). The prevalence of MSI-H tumors in the entire cohort was 18.7%. The prevalence of MSI-H CRC was 22.5% in the group ≤50 years vs. 18.2% in the group >50 years using the age limit in the Amsterdam II guidelines. MSI-H CRC was present in 12.6% of the group aged ≤60 years compared to 20.6% in the control group >60 years.<BR><B>UNASSIGNED: </B>MSI screening of CRC based on age alone is associated with negative selection of a relevant number of cases. MSI-H CRC is also common in elderly patients, who may be negatively selected secondary to an age-based screening algorithm. Following the results of this study, screening based on clinical criteria should be omitted in favor of systematic screening as is already internationally practiced.