P53 NUCLEAR OVEREXPRESSION MAY NOT BE AN INDEPENDENT PROGNOSTIC MARKER IN EARLY COLORECTAL-CANCER

PURPOSE: This study was designed to determine if p53 nuclear overexpression, as detected by immunohistochemistry, is a marker of prognostic significance in early (Stage I) colorectal cancer (CRC). METHODS: Tissue sections obtained from archival blocks of 66 patients with surgically treated Stage 1 CRC were stained immunohistochemically for p53 using a monoclonal antibody (PAB 1801-Ab2). Differences in survival between p53 positive (p53+) and p53 negative (p53-) groups were compared using Kaplan-Meier survival curves and the log-rank test. RESULTS:Thirty-four patients (51.5 percent) were p53+ and 32 (48.5 percent) were p53-. There were significantly more p53+ tumors in females (23 of 34) compared with males (11 of 34) (P = 0.01). Follow-up ranged from 1 to 128.5 (mean, 44.7; median, 38.2) months. Thirteen patients (19.7 percent) developed recurrence, of whom five died of disease. Univariate analysis of clinical and pathologic variables did not reveal any statistically significant differences between p53+ and p53- tumors. Mean actuarial survival was longer (48.2 months) in the p53- group compared with the p53+ group (41.5 months). However, comparison of survival curves using the log-rank test did not show a statistically significant difference in survival (log-rank chi-squared = 0.2; P = 0.6). CONCLUSION: p53 nuclear overexpression does not appear to be an independent marker of prognostic significance in surgically treated early CRC. Females were more likely to have p53+ tumors. The biologic significance of this finding is unknown.