TKFC and neoplasm: Univariate linear regression analysis showed that age (r = 0.242, P = 0.047), tumor size (r = 0.377, P = 0.002), DAK (r = − 0.363, P = 0.002) and DARP (r = − 0.453, P < 0.001) were significantly correlated with operating time (Fig. 1).