Table 3. Results of pooled hazard ratios for overall survival according to clinicopathological parameters.

Outcome		No. of patients	No. of studies	Combined results		Heterogeneity		Statistical Method
				HR(95%CI)	p value	I2 (%)	P value
Age (>60 years)		142	2	1.04 [0.30, 3.61]	0.95	74	0.05	Random model
Gender		3559	6	1.03 [0.94, 1.13]	0.51	34	0.18	Fixed model
PD		7157	6	2.19 [1.29, 3.70]	0.003	93	<0.00001	Random model
positive margins		4936	3	1.96 [1.71,2.24]	< .00001	0	0.54	Fixed model
HTS		317	3	1.72 [1.16, 2.57]	0.007	0	0.6	Fixed model
NLNI		130	2	0.09 [0.04, 0.22]	< .00001	35	0.21	Fixed model

PD: poorly differentiation; HTS: high tumor stage; NLNI: no lymph nodes involved; HR: Hazard Ratio.