Fig. 4

X-tile analysis of cause-specific survival (CSS) data of node positive (N1) NSCLC cases from the SEER registry. a The plot shows the [2] log-rank values produced when dividing the cohort with two cut-points,0.17 and 0.38, producing high, middle, and low subsets (low subset: blue, middle subset: gray, high subset: magenta). The X-axis represents all potential cut-points from low to high (left to right) that define a low subset, whereas the Y-axis represents cut-points from high to low (top to bottom), that define a high subset. The arrows represent the direction in which the low subset (X-axis) and the high subset (Y-axis) increase in size. Red coloration of cut-points indicates an inverse correlation with CSS, whereas green coloration represents direct associations. The optimal cut-point occurs at the brightest pixel (green or red). The cut-point in (a) is shown on a histogram of the entire cohort (b), the relative risk (RR) is displayed in (c) and a Kaplan-Meier plot (d) is drawn. *P < 0.001. A Kaplan-Meier plot is drawn for the CSS of the N2 (e) and N3 (f) subpopulation stratified by the LNR. *P < 0.001