Identification of optimal cutoff values of age of diagnosis via X-tile analysis. a The vertical axis represents all possible high OS populations, with the size of the high OS population increasing from top to bottom. The horizontal axis represents all possible low OS populations, with the size of the low OS population increasing from left to right. Coloration of the plot represents the strength of the association at each division, ranging from low (dark, black) to high (red). b Kaplan-Meier survival curves of three age groups. c The histogram of three age groups
OS, overall survival.