%0 Journal Article
%T Mismatch repair protein deficiency in triple-negative breast carcinomas.
%A Maraqa B
%A Al-Ashhab M
%A Zughaier H
%A Barakat F
%A Khader M
%A Al Maaitah H
%A Alabweh R
%A Sughayer M
%J J Int Med Res
%V 52
%N 6
%D 2024 Jun
%M 38902203
%F 1.573
%R 10.1177/03000605241259747
%X <B>BACKGROUND: </B>Breast cancer, particularly triple-negative breast cancer (TNBC), poses a significant global health burden. Chemotherapy was the mainstay treatment for TNBC patients until immunotherapy was introduced. Studies indicate a noteworthy prevalence (0.2% to 18.6%) of mismatch repair protein (MMRP) deficiency in TNBC, with recent research highlighting the potential of immunotherapy for MMRP-deficient metastatic breast cancer. This study aims to identify MMRP deficiency in TNBC patients using immunohistochemistry.<BR><B>METHODS: </B>A retrospective cohort study design was used and included TNBC patients treated between 2015 and 2021 at King Hussein Cancer Center. Immunohistochemistry was conducted to assess MMRP expression.<BR><B>RESULTS: </B>Among 152 patients, 14 (9.2%) exhibited deficient MMR (dMMR). Loss of PMS2 expression was observed in 13 patients, 5 of whom showed loss of MLH1 expression. Loss of MSH6 and MSH2 expression was observed in one patient. The median follow-up duration was 44 (3-102) months. Despite the higher survival rate (80.8%, 5 years) of dMMR patients than of proficient MMR patients (62.3%), overall survival did not significantly differ between the two groups.<BR><B>CONCLUSIONS: </B>Approximately 9% of TNBC patients exhibit dMMR. dMMR could be used to predict outcomes and identify patients with TNBC who may benefit from immunotherapy.