IL8 expression correlates with ER-negative and high-grade primary breast tumors. Gene set analysis (GSA) of IL8 in a dataset comprising 1,881 primary breast tumors http://co.bmc.lu.se/gobo. (A). IL8 expression correlates with estrogen receptor (ER)-negative tumors. Box plot of IL8 expression in ER-negative and ER-positive primary breast cancers; P < 0.0001 by analysis of variance (ANOVA). B. IL8 expression correlates with high tumor grade. Box plot of IL8 expression in grade 1, 2 and 3 primary breast cancers, respectively; P < 0.0001 by ANOVA. Numbers above the charts show the number of patients in each subtype group.