Natarajan L, et al. - Researchers used the Women's Healthy Eating and Living (WHEL) breast cancer cohort with > 15-years of follow-up, to investigate new miRNAs related to breast cancer survival. They quantified the prognostic value of these miRNAs after adjusting for established clinical factors and genomic markers. Using archived tumor specimens, PAM50 mRNAs and 25 miRNAs were assayed. To ascertain PAM50 subtypes and risk scores (ROR-PT), an existing research-use algorithm was used. In the WHEL and TCGA studies, a link was found between two miRNAs, 210 and 29c, and breast cancer outcomes. These two miRNAs led to further improvement in risk stratification within PAM50 risk groups: 10-year survival was 62% and 75% in the node-negative high miRNA210-high ROR-PT group vs in the low miRNA 210 -high ROR-PT group, respectively. For miRNA 29c, similar outcomes were observed. Via penalized regression, three additional miRNAs (187-3p, 143-3p, and 205-5p) were discovered. Overall, the possible prognostic value of miRNAs for long-term breast cancer survival, as well as their possible utility in improving risk stratification, was suggested in this study.