Highly Sensitive and Specific Detection of Bladder Cancer via Targeted Ultra-deep Sequencing of Urinary DNA

Abstract

BackgroundThere is an unmet need for an accurate, validated, noninvasive test for diagnosing and monitoring bladder cancer (BC). Detection of BC-associated mutations in urinary DNA via targeted deep sequencing could meet this need. ObjectiveTo test the ability of mutational analysis of urinary DNA to noninvasively detect BC within the context of haematuria investigations and non–muscle-invasive BC (NMIBC) surveillance. Design, setting, and participantsCapture-based ultra-deep sequencing was performed for 443 somatic mutations in 23 genes in 591 urine cell-pellet DNAs from haematuria clinic patients and 293 from NMIBC surveillance patients. Variant calling was optimised to minimise false positives using urine samples from 162 haematuria clinic patients without BC. Outcome measurements and statistical analysisThe sensitivity and specificity for BC diagnosis were determined. Results and limitationsMutational analysis of urinary DNA detected 144 of the 165 haematuria patients diagnosed with incident BC from two independent cohorts, yielding overall sensitivity of 87.3% (95% confidence interval [CI] 81.2–92.0%) at specificity of 84.8% (95% CI 79.9–89.0%). The sensitivity was 97.4% for grade 3, 86.5% for grade 2, and 70.8% for grade 1 BC. Among NMIBC surveillance patients, 25 out of 29 recurrent BCs were detected, yielding sensitivity of 86.2% (95% CI 70.8–97.7%) at specificity of 62.5% (95% CI 56.1–68.0%); a positive urine mutation test in the absence of clinically detectable disease was associated with a 2.6-fold increase in the risk of future recurrence. The low number of recurrences in the NMIBC surveillance cohort and the lower sensitivity for detecting grade 1 pTa BC are limitations. ConclusionsDetection of mutations in a small panel of BC-associated genes could facilitate noninvasive BC testing and expedite haematuria investigations. Following further validation, the test could also play a role in NMIBC surveillance. Patient summaryIdentification of alterations in genes that are frequently mutated in bladder cancer appears to be a promising strategy for detecting disease from urine samples and reducing reliance on examination of the bladder via a telescopic camera inserted through the urethra.