Table 1.

The TNM staging system for urachal cancer

The TNM staging system
TNM	Description
Tis	A tumor localized to the urachal mucosa and no invasion to the basal membrane (carcinoma in situ)
T1	A tumor with invasion through the basal membrane
T2	Tumor invades into muscle of the bladder
pT2a	Tumor invades deep muscle of the bladder (outer half)
pT2b	Tumor invades the superficial muscle of the bladder (inner half)
T3	Tumor invades perivesical fat, abdominal wall muscle (in cases of extravesical urachal cancers)
N	Followed the traditional TNM staging system
M	Peritoneal implants were considered metastasis