The impact of androgen receptor (AR) expression on the prognosis of ductal carcinoma in situ (DCIS).

Abstract

e14731 Background: Ductal carcinoma in situ (DCIS) display favorable outcome while little is known about the factors associated with invasive recurrence. To identify better prognostic biomarkers we performed gene expression analysis followed by immunohistochemistry (IHC) staining validation. Methods: Differential gene expression analysis of 29 pure DCIS patients was performed using nanostring platform. RNA was extracted from paraffin blocks from age/size matched 11 recurrence-free and 18 invasive-recurrence cases (disease free interval > 5 years). Gene annotation enrichment analysis was done for differentially expressed genes (DEG) using DAVID. Eighty-two pure DCIS cases were selected for external validation by IHC staining. Allred score cutoff 1 was used for survival analysis. Results: Ninety-nine differentially expressed genes were found statistically significant (p-value < 0.05). Androgen receptor (AR) gene, which encodes a transcription factor AR, has recently been highlighted as a favorable prognostic marker and a therapeutic target in invasive tumor (fold change = - 1.35, p < 0.001). AR protein expression was externally validated by IHC staining of 82 pure DCIS cases (24 invasive-recurrence versus 58 recurrence-free). Similar to gene expression analysis result, patients with invasive recurrence showed lower AR staining score than recurrence-free patients (p = 0.007). Cox regression analysis showed lower AR level as an independent risk factor of long-term invasive recurrence (HR 7.43, 95%CI 1.50 – 36.62). Gene enrichment analysis revealed enrichment of kinase pathway and cell cycle pathway in recurred cases (Enrichment Score = 2.43, 2.41 respectively). Conclusions: DEG pattern was observed among pure DCIS cases. AR may serve as a prognostic biomarker and targeting kinase, cell proliferation may be effective for higher risk DCIS patients.