Table 2. Main results of the meta-analysis.

Categories	Number of datasets	HR	95%CI	P	Degree of heterogeneity (I2 statistics; %)
OS	19	1.48	1.19-1.85	<0.001	37.5
Study quality
Score ≥ 7	10	1.24	0.93-1.65	0.136	44.3
< 7	9	2.04	1.53-2.71	<0.001	0
Sample size
≥ 100	6	1.44	0.98-2.13	0.065	74.3
< 100	13	1.57	1.19-2.07	0.001	0
Duration of follow-up (Months)
> 36	9	1.42	1.04-1.95	0.029	48.7
≤ 36	10	1.56	1.11-2.20	0.01	31.2
Histology types
All	13	1.49	1.06-2.09	0.021	50.9
Serous	6	1.52	1.22-1.88	<0.001	0
Region
European	12	1.44	1.07-1.95	0.016	48.3
North American	3	1.25	0.69-2.26	0.456	33.8
Asian	4	1.95	1.29-2.95	0.002	0
Analysis type
Multivariate	8	1.52	1.01-2.28	0.044	68.2
Univariate	11	1.49	1.21-1.84	<0.001	0

HR: hazard ratio; CI: confidence interval; OS: overall survival.