Luminal A and luminal B (HER2 negative) subtypes of breast cancer consist of a mixture of tumors with different genotype.

Background: The St Gallen International Expert Consensus 2011 has proposed a new classification system for breast cancer. The purpose of this study was to elucidate the relationship between the breast cancer subtypes determined by the new classification system and genomic characteristics.

Methods: Invasive breast cancers (n = 363) were immunohistochemically classified as follows: 111 (30.