PPARgamma expression in breast cancer: clinical value and correlation with ERbeta

To examine the expression of peroxisome proliferator-activated receptor gamma (PPARgamma) in invasive breast carcinoma in relation to known clinicopathological features, ERbeta, and relapse-free and overall patient survival. PPARgamma is a ligand-activated transcriptional factor that regulates the transcription of various target genes and has been implicated in human breast cancer.

We performed immunohistochemistry to detect PPARgamma, ERalpha, PR and ERbeta in 170 infiltrative breast carcinomas. The results were subjected to statistical analysis. PPARgamma was detected in the cytoplasm of 58% of breast carcinoma samples. PPARgamma did not differ with regard to any of the clinicopathological parameters except for histological grade, to which it was found to be inversely correlated (P = 0.019), and ERbeta, to which it was positively related (P = 0.016). As regards relapse-free survival, in univariate statistical analysis PPARgamma was found to exert a marginally favourable impact on all the patients (P = 0.076), but a strong one on patients with ductal carcinoma (P = 0.027), whereas Cox's regression analysis depicted PPARgamma to be an independent prognosticator for patients with ductal carcinoma (P = 0.039). No association was found between PPARgamma expression and overall survival.

These results indicate the favourable impact of PPARgamma expression on disease-free survival of patients with ductal breast carcinoma and its possible cooperation with ERbeta in exerting that favourable effect.