Apoptosis as an independent prognostic indicator in squamous cell carcinoma of the esophagus

Apoptosis plays a crucial role in determining net cell proliferation and cell turnover in various tumors. The rate of apoptosis in tumor cells has been reported to be a useful prognostic indicator in colorectal carcinoma. We examined apoptosis in 72 specimens of esophageal squamous cell carcinoma, by the terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) digoxigenin-nick end labeling (TUNEL) method. We examined correlation of apoptosis with outcome, clinicopathological features, and expression of the apoptosis-related proteins p53 and Bcl-2. The percentage of apoptotic cells, or apoptotic index (Al), ranged from 0.8 to 9.4 (mean: 3.47; SD: 2.02). Overall, 5-year survival of patients with high Al (Al greater than or equal to 5.0; n = 18) tumors was significantly higher than that of patients with low Al tumors (Al < 5.0; n = 58; 76.9% versus 44.9%; P = 0.042). Al did not correlate significantly with the clinicopathological features of patient age and sex, depth of tumor and histological differentiation, lymph node metastasis, lymphatic invasion, or venous invasion. In p53-negative tumors, the Al was significantly higher than in p53-positive tumors. We concluded that Al may be a useful prognostic indicator in esophageal squamous cell carcinoma following curative surgery, and that apoptosis in this tumor is related to relative underexpression of p53 protein.