Lynch syndrome (LS) is an inherited cancer predisposition syndrome caused by pathogenic germline variants in DNA mismatch repair (MMR) genes. New cancer screening and diagnostic tools are urgently needed to identify LS-related cancers early enough for curative treatment. Urothelial cancers (comprising bladder and upper tract urothelial tumors) are the third most common cancer after colorectal and endometrial cancers in individuals with LS. Up to one in four LS individuals will develop urothelial cancer during their lifetime, with the risk varying based on the defective MMR gene. In this clinical trial, we will employ urine tumor DNA (utDNA) to identify asymptomatic urothelial cancers in Lynch syndrome patients, and to investigate the potential benefits of urine tumor DNA based screening in this high-risk population.