Table 3

Analysis of factors for tumour progression

Variable	Categorisation	Tumour progression (TP)
Variable	Categorisation	n*	Events	p Value†
Pathological data
Tumour stage48‡
	pTa	90	10	0.360
	pT1	68	12
Histological grade48‡
	G1	44	3	0.085
	G2	86	12
	G3	28	7
Histological grade49§
	Low grade	99	10	0.083
	High grade	59	12
Adjacent carcinoma in situ
	No	146	20	0.545
	Yes	12	2
Multiplicity
	Unifocal tumour	115	15	0.465
	Multifocal tumour	43	7
Growth pattern
	Papillary	151	17	<0.0001
	Solid	7	5
Immunohistochemistry
Cx43
	Score 0 or 1+	130	12	<0.0001
	Score 2+	28	10
Ki-67 labelling index
	≤10%	106	9	0.003
	>10%	52	13

*Only primary pTa and pT1 tumours are included.
†Log-rank test (two-sided); bold face representing p values <0.05.
‡Staging and grading according to the 1973 WHO classification system.
§Staging and grading according to the 2004 WHO classification system.