{"entity":{"id":"paper-kurata-japanese-tnbc-msi-breast-cancer-2020","kind":"paper","name":"Microsatellite instability in Japanese female patients with triple-negative breast cancer","aka":[],"tldr":"Two of 228 Japanese triple-negative breast cancers, under 1%, were MSI-high; both were aggressive basal-like tumours without BRCA-like features.","summary":"MSI in 228 TNBCs was evaluated with the Promega MSI Analysis System 1.2 (BAT-26, NR-21, BAT-25, MONO-27, NR-24) without normal tissue controls. 222 (97.4%) were stable, 4 (1.7%) MSI-low and 2 (0.9%) MSI-high; the two MSI-high tumours were nuclear grade 3, Ki-67 above 30%, basal-like and non-BRCA-like, with inconsistent TILs, CD8 and PD-L1.","asOf":"2026-09-24","links":[{"label":"Kurata et al., Breast Cancer 2020: MSI in 228 Japanese TNBC patients","url":"https://doi.org/10.1007/s12282-019-01043-5"},{"label":"PubMed","url":"https://pubmed.ncbi.nlm.nih.gov/31907878/"}],"tags":[],"related":["msi-high"],"cancers":["tnbc"],"sections":[],"technologies":[],"targets":["mmr"],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["msi"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":["breast-cancer-jbcs"],"dependsOn":[],"notes":[],"journal":"Breast Cancer","year":2020,"doi":"10.1007/s12282-019-01043-5","pmid":"31907878","authors":"Kurata K, Kubo M, Kai M, et al.","paperType":"observational","findings":["MSI-high 2 of 228 (0.9%); MSI-low 1.7%.","MSI-high tumours were grade 3, Ki-67-high and basal-like."],"whatItMeans":"Rare MSI-high TNBC exists and qualifies for tumour-agnostic pembrolizumab, so comprehensive genomic profiling should report MSI even though dedicated testing is low-yield.","caveats":["No matched normal; small numbers of positives.","Japanese single-region cohort."],"changedPractice":false,"participants":228},"route":"/key-papers/paper-kurata-japanese-tnbc-msi-breast-cancer-2020/","neighbours":{"biomarker":[{"id":"msi-high","kind":"biomarker","name":"MSI-high (microsatellite instability by PCR or sequencing)","route":"/biomarkers/msi-high/"}],"cancer":[{"id":"tnbc","kind":"cancer","name":"Triple-negative breast cancer (TNBC)","route":"/cancers/tnbc/"}],"target":[{"id":"mmr","kind":"target","name":"Mismatch repair proteins (MLH1, MSH2, MSH6, PMS2)","route":"/targets/mmr/"}],"term":[{"id":"msi","kind":"term","name":"Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)","route":"/terms/msi/"}],"journal":[{"id":"breast-cancer-jbcs","kind":"journal","name":"Breast cancer","route":"/journals/breast-cancer-jbcs/"}]}}