The primary outcome of new cancer diagnosis or new malignant histological specimen occurred in 140 of 678 patients ( 21 % ) in the 80 % oxygen group vs 150 of 699 patients ( 21 % ) assigned to 30 % oxygen ; hazards ratio 1.06 [ 95 % confidence interval ( CI ) 0.84 , 1.34 ] , P = 0.62 .