In order to assess the feasibility of using DNA methylation as a biomarker for cancer detection and recurrence monitoring, genes showing highest methylation frequency (p14, DAPK, SFRP1, and IRF8) in tumor tissues from Taiwan samples and RASSF1A which have been previously found to be methylated in bladder cancer patients [12,22,31] were selected as potential targets for methylation detection in urine samples that were acquired retrospectively from a different patient pool from Taiwan. The gene discussed is RASSF1; the disease is urinary bladder cancer.