Supplementary Material for: Prognostic Value of Pre- and Postoperative Anti-p53 Antibody Levels in Colorectal Cancer Patients: A Retrospective Study

<p><b><i>Objective:</i></b> To determine the utility of the post-/preoperative anti-p53 antibody (p53 Ab) ratio as a prognostic factor for colorectal cancer (CRC) recurrence. <b><i>Methods:</i></b> A total of 737 nonmetastatic CRC patients who had undergone R0 resection were retrospectively analyzed. p53 Ab levels were measured within 1 month prior to and at least every 3 months after surgery. Post-/preoperative p53 Ab ratios were calculated, and the optimal ratio cutoff values for predicting recurrence were determined using the Kaplan-Meier method and the log-rank test. <b><i>Results:</i></b> Preoperative p53 Ab elevation was observed in 194 patients (pre-p53 high). Preoperative p53 Ab levels correlated with TNM stage. Re-elevation of p53 Ab levels occurred on recurrence in the pre-p53 high group, but not in the pre-p53 low group (n = 543). In the pre-p53 high group, patients who experienced tumor recurrence exhibited a slow postoperative reduction of p53 Ab levels, and a post-/preoperative p53 Ab ratio >0.4 at postoperative 3 months predicted relapse-free survival. In other words, a p53 Ab level remaining higher than 40% of the preoperative level was an independent and strong risk factor for recurrence in multivariate analyses. <b><i>Conclusion:</i></b> In CRC patients with preoperative p53 Ab elevation, the rate of p53 Ab reduction in the early postsurgical period is a promising prognostic factor for recurrence.</p