High sensitivity ctDNA assays in genitourinary malignancies: current evidence and future directions

In the recent decade, analysis of circulating tumor DNA (ctDNA) has improved cancer care by allowing for rapid detection of actionable molecular targets. A new generation of circulating DNA tests is now becoming available commercially. These tests are characterized by a superior limit of detection of 0.01% vaF or better, allowing for the detection of radiologically occult molecular residual disease (MRD). MRD tests have the potential to revolutionize neoadjuvant and adjuvant treatment. In addition, these tests can be used as tumor markers to assess disease response. We reviewed the current evidence for the use of high-sensitivity MRD assays with particular focus on the genitourinary tumors. Multiple studies have now been reported in urothelial, renal, and recently testicular carcinoma. We find that the sensitivity varies across tumor types in the adjuvant setting and may reach a high of 100% in urothelial cancer. Specificity in tumor-informed MRD appears to be preserved across tumor types (98%-100%). Several trials are now prospectively validating MRD testing in biomarker integral studies, mainly in urothelial carcinoma.