The Prognostic Value of Different Molecular Subtypes of Breast Cancer in Relation to Enhancer-of-Zeste Homologue 2 Expression XC01-XC06
Hematology and Oncology Research Center, Tabriz University of Medical Sciences, Tabriz, East Azerbaijan, Iran.
Introduction: The role of Enhancer-of-zeste homologue 2 (EZH2) in breast cancer invasion and progression may be attributed to EZH2-mediated epigenetic repression of tumour cells.
Aim: The study aimed to assess the prognostic value of different luminal subtypes of breast cancer in association with EZH2 protein expression.
Materials and Methods: A cross-sectional analytical research study on breast cancer women was performed. The four major molecular subtypes of breast cancer were defined, as follows: luminal A, luminal B, HER2-type, and Triple-Negative/Basal-like (TNBC). Log Rank (Mantel-Cox) test of equality of survival function was then performed to assess statistical significance between groups. The effects of variables on Overall Survival (OS) and Event Free Survival (EFS), was then assessed to give adjusted Hazard Ratios (HRs) with 95% Confidence intervals (CIs).
Results: Samples were collected for women with breast cancers, with follow-up data collected over a 5-year period, with the age range of 34-75 years. TNBC subgroup was twice as likely to have high EZH2 expression compared with the luminal A subgroup (as the reference group) (OR=2.06; 95% CI=0.22 to19.09), and the luminal B subgroup had a 35% reduced likelihood (OR=0.66; 95% CI=0.26 to1.70). Cox’s Regression analysis showed that the hazard of mortality was about 3 times more in HER2 subtype breast cancers than in the luminal A subgroup (HR=3.16; 95% CI: 1.30-15.45, P<0.005), while the Log Rank (Mantel-Cox) test showed a statistically significant difference in OS by molecular subtype at all-time points (p=0.05).
Conclusion: The results provide some interesting insights, confirming the prognostic differences by molecular subtypes, in relation to EZH2 protein expression. However, there remains controversy about the prognostic value of different molecular subtypes.