Table 2. Egger’s test of publication bias.

	Coeff.	Std. Err.	t	P>|t|	[95% CI]
High-grade and low-grade	−0.46	0.39	−1.16	0.27	−1.33	0.40
Invasive and superficial	−3.23	0.25	−1.31	0.22	−8.9	0.23