A new test for bladder cancer could enable general practitioners to test a urine sample and spare patients the discomfort of a cystoscopy in hospital which is the gold standard test for the detection of bladder cancer, but it is operator-dependent with a sensitivity of 90% to 97%.
DNA methylation is ontogenically relatively stable, a property which can be exploited to develop diagnostic assays resulting in an active area of studies in the field of urinary-based biomarkers for the non-invasive detection of bladder cancer (BC).
An international team of scientists working with this at the University College London performed genome-wide DNA methylation profiling on DNA from 86 bladder cancers and 30 age-matched normal urothelium samples obtained from biorepositories. Pathological review of representative hematoxylin and eosin (H&E) sections was conducted to include only specimens with tumor cellularity of greater than 80%.
The biomarker assay, known as The UroMark panel, was defined using pre-set criteria in the training cohort as follows: in order for probes to be considered as potential biomarker candidates, they had to show no or very low methylation (β less than 10%) in normal urothelium, blood and non-cancer urine samples and methylation (β) of greater than 50% in bladder cancer. RainDrop BS-seq was performed where the bisulfite-treated genomic DNA template mix was then applied to a fully automated ThunderStorm system.
The scientists defined a 150 CpG loci biomarker panel from a cohort of 86 muscle-invasive bladder cancers and 30 normal urothelium. Based on this panel, they developed the UroMark assay, a next-generation bisulphite sequencing assay and analysis pipeline for the detection of bladder cancer from urinary sediment DNA. The 150 loci UroMark assay was validated in an independent cohort of 274, 167 were non-cancer and 107 with bladder cancer in voided urine samples with an AUC of 97%. The UroMark classifier sensitivity of 98%, specificity of 97% and a negative predictive value (NPV) of 97% for the detection of primary BC was compared to non-BC urine.
John D. Kelly, MD, FRCS, a professor of Uro-Oncology, and senior author of the study, said, “We have good evidence that patients, particularly females, are diagnosed late with bladder cancer and often patients visit a GP several times with symptoms prior to detection. Having the UroMark test available to GPs will mean that patients can be tested at an early stage to rule out bladder cancer.” The study was published on January 31, 2017, in the journal Clinical Epigenetics.
