Fig. 3

Cancer-specific survival (a) of patients with lung cancer in the SEER database are stratified using the optimal cut-off points (0.28 and 0.81) of lymph node ratio (LNR) by X-tile analysis: LNR1 ≤ 0.28; 0.28 < LNR2 < 0.81; LNR3 > 0.81. Forest plots showing results of multivariate Cox regression analysis using LNR as a covariate for prediction of CSS (b). Forest plots showing results of multivariate Cox regression analysis using pN as a covariate for prediction of CSS (c). On the basis of the Cox model, prespecified subgroup analyses of covariates of interest were conducted to estimate hazard ratios (HR) with 95% confidence intervals (CI) and to test for interaction among subgroups with the use of two-sided P values. A HR of less than 1 implies a lower risk of death