Are triple-negative tumours and basal-like breast cancer synonymous?

Excerpt

Kreike and colleagues [1] examined the gene expression and pathological characteristics of a retrospectively accrued cohort of 97 triple-negative phenotype (TNP) (oestrogen receptor [ER]-negative, progesterone receptor-negative, and HER2-negative) invasive breast cancers. TNP tumours were profiled with oligonucleotide microarrays and compared with a control group of 102 non-TNP tumours, which were obtained from an unrelated project. The authors then investigated whether the TNP would accurately identify basal-like cancers, by assessing the correlation coefficient between the gene expression profiles of each TNP cancer and the centroids of the molecular subgroups as defined by Hu and colleagues [2]. As expected, the majority (91%) of TNP tumours were classified as 'basal-like' tumours. However, 9% of tumours either showed a normal-like phenotype or were unclassifiable [1]. The authors presented a hierarchical clustering analysis of both TNP and control cases, based on a partial 'intrinsic gene list' and a different reference RNA when compared with those reported by Hu and colleagues [2], and observed that all of the TNP group and 18.6% of the control non-TNP group clustered together [1]. Based on the above results, the authors drew the provocative conclusions that 'basal-like tumours can be reliably defined by triple-negative immunohistochemistry' and that 'triple-negative tumours are synonymous with basal-like tumours'. …