Progression-free survival was significantly longer in the olaparib plus chemotherapy group ( median 12.2 months [ 95 % CI 9.7-15 .0 ] ) than in the chemotherapy alone group ( median 9.6 months [ 95 % CI 9.1-9 .7 ) ( HR 0.51 [ 95 % CI 0.34-0 .77 ] ; p = 0.0012 ) , especially in patients with BRCA mutations ( HR 0.21 [ 0.08-0 .55 ] ; p = 0.0015 ) .