Evolution of microsatellite instability testing in a population-based cohort of patients with colorectal cancer in France in the years leading up to official recommendations
摘要
Guidelines for systematic microsatellite instability (MSI) testing in colorectal cancer have emerged in recent years, and more specifically in France since November 2021. Besides detection of Lynch syndrome for early detection of other cancer and family screening, MSI is associated with different treatment options depending on cancer stage. The aim of this study was to describe MSI testing frequency in patients with colorectal cancer in a French region in the years leading up to the publication of official guidelines.
MethodsCases from the Calvados digestive cancer registry were studied between 2019 and 2021. Age, sex, socioeconomic deprivation, tumour location, stage at diagnosis, progression, type of hospital for surgery and for multidisciplinary meetings were collected. These characteristics were compared between cases that underwent testing and those that didn’t, and between unstable and stable cases when tested, using descriptive analyses.
ResultsA total of 1169 cases were included, of which 60% were tested for MSI. Younger patients (80% of patients under the age of 65 vs. 57% of patients over the age of 80) and more advanced stages were more frequently tested (52% stage I vs. 70% stage IV). A higher proportion of cases was tested in 2021 than in 2019 and 2020. A higher proportion of colon cancer cases were tested than rectal cancer (75% vs. 61%). Of the 816 cases tested, 13.6% had MSI. A higher percentage of colon cancer cases were unstable compared to rectal cancer cases (19% vs. 2%). When the analysis was restricted to the year 2021, 18% of cases remained untested. The only significant differences remaining in 2021 were for location (more frequent for colon than for rectal cancer cases), and for stage at diagnosis (performed less for stage I).
ConclusionsThis population-based French study reveals disparities before emergence of official national guidelines and the reduction in these disparities in the most recent years. However, achievement of systematic testing was not yet attained in 2021.