RT Journal Article
SR Electronic
T1 2022-RA-967-ESGO Endometrial cancer: agreement between microsatellite instability in immunohistochemistry and molecular biology?
JF International Journal of Gynecologic Cancer
JO Int J Gynecol Cancer
FD BMJ Publishing Group Ltd
SP A123
OP A124
DO 10.1136/ijgc-2022-ESGO.266
VO 32
IS Suppl 2
A1 Christine Gennigens
A1 Adriane Dheur
A1 Vincent Bours
A1 Katty Delbecque
A1 Elodie Gonne
A1 Clemence Pleyers
A1 Laurence Seidel
A1 Sylvie Streel
A1 Marjolein de Cuypere
A1 Frederic Goffin
A1 Pierre Lovinfosse
A1 Athanasios Kakkos
A1 Frederic Kridelka
A1 Alixe Salmon
YR 2022
UL http://ijgc.bmj.com/content/32/Suppl_2/A123.abstract
AB Introduction/Background Endometrial carcinoma (EC) is the most common cancer of the female genital tract in developed countries. Microsatellite instability (MSI), that represents 30% of EC, is an important prognostic and predictive biomarker. This status is assessed by detection of loss of MMR genes’ proteins by immunohistochemistry (IHC) or by molecular biology. We aimed to compare the agreement between MSI status in IHC and molecular biology.Methodology Between January 2019 and December 2021, we conducted a monocentric retrospective study of 166 patients treated for EC (all stages) at the CHU of Liège. Sixty-seven patients were excluded. The remaining 99 patients had a complete IHC and molecular analysis for MSI. McNemar’s test and a Kappa of Cohen coefficient were used to evaluate the agreement between the 2 methods.Results The McNemar’s test demonstrated 41.4% and 39.4% of MSI in IHC and molecular biology, respectively (p=0.81). There were ten tumors with false-positive staining in IHC and MSS in molecular biology (specificity of 75.6%). Moreover, there were eight tumors with false-negative IHC but MSI-H in molecular analysis (sensitivity of 85.2%). The agreement between MSI in IHC and molecular analysis was 81/99 (81.8%) patients. The Kappa of Cohen coefficient was 0.62 (IC95%: 0.47–0.78), confirming the agreement between both techniques.Conclusion The methods of testing MSI by IHC and molecular biology are clearly concordant. Presence of MSI in IHC can be considered as a reliable surrogate test for MSI molecular status. Moreover, IHC testing is quicker, easier to perform and less expensive. Nevertheless, based on a 25% and 15% rate of false positivity and negativity respectively, consideration should be given to confirm MSI IHC status for all patients by molecular analyses.