Table 1. The advantages and disadvantages of various approaches to the analysis of urinary tDNA.

Method	Disadvantages	Advantages
DNA methylation	Relatively large amount of DNA required	Very high specificity and sensitivity recently reported (7)
	Influenced by other factors (age, smoking)
Copy number changes	Unable to detect low levels of tumour DNA in a high background of non-tumour DNA	High specificity and most UBCs have copy number changes (10)
Microsatellite analysis	Unable to detect low levels of tumour DNA in a high background of non-tumour DNA	Good sensitivity and specificity reported (11)
	Multiple individual tests needed
Mutations	Multiple mutations must be analysed to achieve high sensitivity	High specificity and can detect low levels of tumour DNA in a high background of non-tumour DNA (8,12,13)

tDNA, tumour DNA; UBCs, urothelial bladder cancers.