The levels of interleukin-6 ( IL-6 ) at 3 days after the operation also differed significantly between the 3 groups but were lower in all the 3 groups than those at 1 day after the operation ( P = 0.046 ) , and this reduction was the most obvious in group A. COX-2 expression differed significantly between the 3 groups ( P = 0.017 ) , among which group A showed the most obvious suppression of COX-2 expression .