Distribution of molecular breast cancer subtypes in middle eastern-saudi arabian women: a pilot study.

Increasing evidence suggests the possibility of relevant molecular differences between cancers from different ethnic groups. This study uses gene expression profiling by quantitative real time polymerase chain reaction (qRT-PCR) to identify "intrinsic" subtypes in a Saudi population of breast cancers and compares the distribution of subtypes to the more commonly profiled Caucasian population. In addition, the immunohistochemical profile of breast cancers was correlated to the gene expression analysis. Discrepancy rate of 39% in subtype prediction between gene expression and immunohistochemical profile of the tumors was noticed. Most of this variation was in the luminal subtype. Frequency of HER2+ subtype in the Saudi cases was high (28%) by both the immunohistochemistry (IHC) and the qRT-PCR classification. Triple-negative tumors comprised 39% while only 11% showed a basal-like profile. Analysis of larger cohort of patients is needed to determine the molecular taxonomy of breast cancer in the Saudi population and the benefits from the diagnostic classification developed in the West.