Distribution of Molecular Breast Cancer Subtypes in Middle Eastern-Saudi Arabian Women: A Pilot Study

Abstract

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.

Triple-negative breast cancer in Hispanic patients

“…In a subsequent study of 255 patients with TNBC, 49 patients (19.2%) were Hispanic Americans. 31 The prevalence of TNBC varies according to ethnicity and has been reported as high as 82% in Ghana, 32 39% in Saudi Arabia, 33 19.3% in China, 32 and 15.9% in Taiwan. 34 The distribution according to clinical disease stage in our study population (localized disease, 44.3%; regional disease, 44%; and distant disease, 11.7%) was similar to that reported in African-American patients (51%, 37%, and 10%, respectively) 1 and Hispanic-American patients (54%, 37%, and 7%, respectively) with breast cancer.…”

The Spectrum of Genetic Mutations in Breast Cancer

“…A Saudi study demonstrated by immunohistochemistry that the frequency of HER2+ breast cancer cases can be as high as 28% (Al-Tamimi et al, 2009). In 25-30% of the breast cancer cases, the ERBB2 gene is amplified (Tan and Yu, 2007).…”

Protein expression profile and prevalence pattern of the molecular classes of breast cancer - a Saudi population based study

“…Studies confirmed that it could reliably identify the major molecular subgroups of invasive breast carcinoma [14-16]. Recently published studies have used five IHC surrogate markers (ER, PR, HER2, CK5/6, and EGFR) for molecular class distinction [17-19], with luminal tumors being categorized by hormone receptor (HR) positivity, HER2 expression a feature of HER 2 tumors, and CK5/6 and/or EGFR indicative of basal-like tumors. The molecular dimensions were further diversified by the introduction of a hybrid category comprising the HER2 + luminal tumors [20].…”

“…We initially conducted a pilot study in which gene expression profiling by real time quantitative PCR was used to determine the "intrinsic" Saudi breast cancer subtypes and its prevalence was compared to the more commonly profiled Caucasian population [19]. A comparison between the IHC profiles of these breast cancers was correlated to the gene expression analysis and a discrepancy rate of 39% was identified, most conspicuously in the luminal type.…”