Table 2. Pairwise correlation between tumour characteristics (Pearson's product moment correlation, Bonferroni correction).

Characteristic	Tumour size	Necrosis	Vascular invasion	Histological grade	Tumour depth	Location
Tumour size	1
Necrosis	0.41***	1
Vascular invasion	0.16**	0.29***	1
Histological grade	0.23***	0.55***	0.30***	1
Tumour depth	0.36***	0.18***	0.11	0.14*	1
Location	−0.02	0.00	0.03	−0.05	−0.05	1

^***P<0.0001, ^** P<0.001, ^* P<0.01.