Multivariate Cox proportional hazards regression analysis revealed the type of treatment ( hazard ratio , 0.434 ; 95 % CI , 0.293 to 0.644 , p < 0.001 ) , number of tumor ( hazard ratio , 1.758 ; 95 % CI , 1.213 to 2.548 , p = 0.003 ) and gender ( hazard ratio , 0.451 ; 95 % CI , 0.236 to 0.862 , p = 0.016 ) were significant independent risk factors associated with OS .