biostudies-literatureThennavan ABreast Cancer Research FoundationSusan G. KomenNational Cancer InstituteNCI NIH HHSUniversity of North Carolina at Chapel Hill100067https://www.ebi.ac.uk/biostudies/studies/S-EPMC9028992biostudies-literatureUnknown1(3)Breast cancer is classified into multiple distinct histologic types, and many of the rarer types have limited characterization. Here, we extend The Cancer Genome Atlas Breast Cancer (TCGA-BRCA) dataset with additional histologic type annotations, in a total of 1063 breast cancers. We analyze this extended dataset to define transcriptomic and genomic profiles of six rare special histologic types: cribriform, micropapillary, mucinous, papillary, metaplastic, and invasive carcinoma with medullary pattern. We show the broader applicability of our constructed special histologic type gene signatures in the TCGA Pan-Cancer Atlas dataset with a predictive model that detects mucinous histologic type across cancers of other organ systems. Using a normal mammary cell differentiation score analysis, wCell genomicsMolecular analysis of TCGA breast cancer histologic types.PMC9028992RO1-CA195740P50 CA058223R01 CA195740R01 CA148761P50-CA58223SAC-160074RO1-CA148761Xia YAllison KCollins LCBeck AThennavan ASchnitt SJHoadley KAChen YYBeca FTse GMPerou CMRecio SGfalseMolecular analysis of TCGA breast cancer histologic types.Breast cancer is classified into multiple distinct histologic types, and many of the rarer types have limited characterization. Here, we extend The Cancer Genome Atlas Breast Cancer (TCGA-BRCA) dataset with additional histologic type annotations, in a total of 1063 breast cancers. We analyze this extended dataset to define transcriptomic and genomic profiles of six rare special histologic types: cribriform, micropapillary, mucinous, papillary, metaplastic, and invasive carcinoma with medullary pattern. We show the broader applicability of our constructed special histologic type gene signatures in the TCGA Pan-Cancer Atlas dataset with a predictive model that detects mucinous histologic type across cancers of other organ systems. Using a normal mammary cell differentiation score analysis, w2021-01-01T00:00:00Z2021 Dec2026-05-10T01:01:04.383Z2025-04-07T01:52:44.895ZS-EPMC90289923546540010.1016/j.xgen.2021.100067