{"entity":{"id":"paper-foulkes-brca1-basal-phenotype-jnci-2003","kind":"paper","name":"Germline BRCA1 mutations and a basal epithelial phenotype in breast cancer","aka":[],"tldr":"A 2003 study using an ordinary pathology stain, cytokeratin 5/6, to show that breast cancers in women with an inherited BRCA1 fault are nine times more likely to have the basal pattern; it brought the basal-like idea from the microarray to the pathology bench.","summary":"Foulkes, Stefansson, Chappuis, Bégin and colleagues tested whether BRCA1-related breast cancers are more likely than non-BRCA1/2 cancers to express a basal epithelial phenotype, found in at most 15 percent of invasive breast cancers and associated with oestrogen receptor- and HER2-negative tumours. Among 292 specimens previously analysed for oestrogen receptor, HER2, p53 and germline BRCA1 and BRCA2 mutations, 76 were negative for both receptors; of 72 with sufficient material, 40 expressed cytokeratin 5 and/or 6. Cytokeratin 5/6 expression was significantly associated with BRCA1-related cancer (odds ratio 9.0, 95 percent confidence interval 1.9 to 43; p=0.002).","asOf":"2026-09-24","links":[{"label":"J Natl Cancer Inst 2003","url":"https://doi.org/10.1093/jnci/djg050"},{"label":"PubMed","url":"https://pubmed.ncbi.nlm.nih.gov/14519755/"}],"tags":["tnbc-evidence"],"related":["paper-sorlie-repeated-observation-subtypes-brca1-basal-pnas-2003","paper-carey-race-breast-cancer-subtypes-cbcs-jama-2006"],"cancers":["tnbc"],"sections":[],"technologies":[],"targets":["brca"],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["ihc","germline-testing"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":["jnci"],"dependsOn":[],"notes":[],"journal":"Journal of the National Cancer Institute","year":2003,"doi":"10.1093/jnci/djg050","pmid":"14519755","authors":"Foulkes WD, Stefansson IM, Chappuis PO, et al.","paperType":"translational","findings":["Among 72 oestrogen receptor- and HER2-negative tumours, cytokeratin 5/6 expression was associated with germline BRCA1 mutation: odds ratio 9.0 (95 percent CI 1.9 to 43), p=0.002."],"whatItMeans":"Confirmed the BRCA1 to basal link with a stain any laboratory could run, which is how the basal-like concept reached clinical pathology and how the Carolina Breast Cancer Study defined its subtypes three years later.","caveats":["Small numbers and a wide confidence interval.","Cytokeratin 5/6 is a surrogate; the immunohistochemical definition of basal-like was never standardised."],"changedPractice":false,"participants":292},"route":"/key-papers/paper-foulkes-brca1-basal-phenotype-jnci-2003/","neighbours":{"paper":[{"id":"paper-carey-race-breast-cancer-subtypes-cbcs-jama-2006","kind":"paper","name":"Race, breast cancer subtypes, and survival in the Carolina Breast Cancer Study","route":"/key-papers/paper-carey-race-breast-cancer-subtypes-cbcs-jama-2006/"},{"id":"paper-sorlie-repeated-observation-subtypes-brca1-basal-pnas-2003","kind":"paper","name":"Repeated observation of breast tumor subtypes in independent gene expression data sets","route":"/key-papers/paper-sorlie-repeated-observation-subtypes-brca1-basal-pnas-2003/"}],"cancer":[{"id":"tnbc","kind":"cancer","name":"Triple-negative breast cancer (TNBC)","route":"/cancers/tnbc/"}],"target":[{"id":"brca","kind":"target","name":"BRCA1 / BRCA2 (HRD)","route":"/targets/brca/"}],"term":[{"id":"ihc","kind":"term","name":"Immunohistochemistry (IHC)","route":"/terms/ihc/"}],"technology":[{"id":"germline-testing","kind":"technology","name":"Germline (hereditary) testing","route":"/technologies/germline-testing/"}],"journal":[{"id":"jnci","kind":"journal","name":"JNCI: Journal of the National Cancer Institute","route":"/journals/jnci/"}],"roadmap":[{"id":"tnbc-roadmap","kind":"roadmap","name":"Triple-negative breast cancer roadmap: from a remainder defined by three negative tests to immunotherapy, antibody-drug conjugates and the residual disease problem","route":"/roadmaps/tnbc-roadmap/"}]}}