Figure 3

Estrogen receptor-positive breast cancer subsets by gene set enrichment analysis. Assessment of estrogen receptor (ER)-positive breast cancer subsets by gene set enrichment analysis (GSEA) for specific gene signatures. (a) Unsupervised clustering of the 101 primary ER-positive breast cancers shown in Figure 2 based only on expression of the 71-gene proliferation signature shown to be significant by GSEA, revealing two major clusters (high expressors and low expressors of proliferation signature) with significant biases in age and ERBB2 status; horizontal colored bars identify the age cohort, progesterone receptor (PR) status and ERBB2 status of the samples in each column. (b) Kaplan–Meier plots of recurrence events among the 54 ER-positive cases with known clinical follow-up, dichotomized by high (red) or low (green) expression of the 71-gene proliferation signature, with significance determined by log-rank analysis.