Kaplan–Meier curve for survival at follow-up according to different preoperative baseline classifications in stages. At 5 years, survival was 100% in stage 2 (red line), 88.2 ± 4.26% in stage 3 (blue line) and 60.4 ± 8.45% in stages 4 and 5 (green line) (P = 0.001). A colour version of this figure appears in the online version of this article.