ORLANDO, FL USA (UroToday.com) - The detection of small renal masses (SRMs) < 4cm in size have given rise to the widespread use of abdominal imaging.
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Twenty to 30% of SRMs are benign and workup and management remains controversial with advocates for biopsy, surveillance, or surgical treatment. Thus, accurate characterization of SRMs is needed to determine treatment. Needle biopsies of SRMs have high false-negative rates on standard microscopic examination (10–20%) since small amounts of tissue are sometimes obtained. The study group aimed to identify epigenetic markers to improve the diagnostic value of renal needle biopsies.
After gaining IRB approval, needle biopsies were obtained ex vivo in 100 patients with SRMs undergoing partial nephrectomy. Each lesion underwent 3 pairs of biopsies: 2 from tumor regions and 1 from adjacent normal tissue; one was examined and the other was used for DNA extraction. The methylation levels of these samples at select CpG dinucleotides throughout the genome were detected using the Infinium 450K array technology. To elucidate tissue-specific DNA methylation markers, these biological values were then compared to Infinium 450K data derived from 300 categorized renal samples from The Cancer Genome Atlas (TCGA).
A total of 60 SRMs have been examined to date. The research group isolated 9 432 candidate markers of differential DNA methylation with average beta value difference between two sample groups of >0.4. Current efforts have been made to create an algorithm that allows us to predict the type of tissue based on methylation markers. To date, the algorithm has shown to successfully predict normal and cancerous tissue at a sensitivity rate of 91% and 90%, respectively.
The authors conclude that preliminary results suggest significant differences in DNA methylation levels exist at specific sites in the human genome among normal and aberrant kidney tissues. It's likely these biomarkers can be used to distinguish tissue types. They use statistical approaches to identify a panel of DNA methylation markers to improve predicting phenotype and develop an economically efficient method for distinguishing between benign and cancer tissues.
Presented by Sameer Chopra, MD at the American Urological Association (AUA) Annual Meeting- May 16 - 21, 2014 - Orlando, Florida USA
Los Angeles, CA USA
Written by Achim Lusch, MD, University of California (Irvine), and medical writer for UroToday.com