Table 2. Main characteristics of the studies for OS.

Study	HR (95%C I) of OS in univariate	HR (95%C I) of OS in Cox multivariate	HR (95%C I) of OS not limited to curative RT dose
Liao ZX 2010	NG	0.64 (0.41–0.98) P = 0.039	NG
Harris JP 2014	0.90 (0.82–0.98) P = 0.02	0.94 (0.85–1.04) P = 0.23	0.94 (0.85–1.04) P = 0.23
Hsia TC 2014	NG	1.54 (0.82–2.91) P = 0.18	NG
Chen AB 2014	0.95 (0.87–1.0) P = 0.24	0.99 (0.9–1.09) P = 0.82	0.89 (0.84–0.99) P = 0.03
Noh JM 2015	NG	2.16 (0.67–6.96) P = 0.197	NG