Briefly, tissue sections were deparaffinized, soaked in Tris-EDTA buffer (pH 8.0) and boiled in the microwave, then incubated with the primary antibodies at 4°C overnight. Next day, slides were washed and stained by the secondary antibody and DAB disclosure, counterstained with hematoxylin, dehydrated and mounted. The sections were reviewed and scored independently by two observers. Degree of immunostaining was determined based on both the proportion of positively stained tumor cells and the intensity of staining. The proportion of positive tumor cells was scored as follows: 0, no positive tumor cells; 1, < 10%; 2, 10%–35%; 3, 35%–75%; 4, > 75%. The intensity of staining was graded according to the following criteria: 1, weak staining (light yellow); 2, moderate staining (yellow–brown); 3, strong staining (brown). The IHC score was calculated as staining intensity score × proportion of positive tumor cells. Using this method of assessment, the expression of p-DNA-PKcs was scored as 0, 1, 2, 3, 4, 6, 8, 9, and 12. High expression of p-DNA-PKcs and p-AKT referred to IHC score ≥ 6 and low expression of p-DNA-PKcs and p-AKT was defined as IHC score < 6.