To determine the utility of the post-/preoperative anti-p53 antibody (p53 Ab) ratio as a prognostic factor for colorectal cancer (CRC) recurrence.

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.

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.

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.