DNA methylation status predicts survival in metastasis free clear cell renal cell carcinoma. DNA methylation status predicts survival in metastasis free clear cell renal cell carcinoma

Background: Clear cell renal cell carcinomas (ccRCCs) display divergent clinical phenotypes. Up to one third of patients with local disease at diagnosis will progress. Therefore, it is a need to identify patients at risk for recurrence. In the present study, we analyzed genome-wide promoter DNA methylation at diagnosis in relation to clinicopathological parameters, in order to identify DNA methylation profiles associated with risk for progress. Method: DNA methylation status in 155,931 CpGs located in gene promoter regions was analyzed by Illumina HumanMethylation450K arrays in diagnostic tissue samples from 115 ccRCC patients. Methylation profiles were compared with genetic aberrations and clinicopathological parameters. Results: The tumors separated into two clusters based on genome-wide promoter methylation status. The tumors in these clusters differed in tumor diameter (p 0.001), and predicted mitotic age (R = 0.407, p < 0.001). Conclusion: DNA methylation analysis at diagnosis in ccRCC has the potential to improve outcome-prediction and therapy stratification. Overall design: Bisulphite converted DNA from the clear cell renal cell carcinoma tumors and tumor free tisssue samples were hybridised to the Illumina Infinium 450k Human Methylation Beadchip