Prognostic value of DNA index, S-phase fraction and p53 protein accumulation after surgical resection of esophageal squamous-cell carcinomas in Thailand.

The prognostic value of cell nuclear DNA content, S-phase fraction and p53 protein accumulation in esophageal squamous-cell carcinomas was studied in a consecutive series of 80 patients from a high-incidence region of southern Thailand, who underwent esophagectomy between 1983 and 1993. Flow cytometry was used to determine tumor ploidy, DNA index and S-phase fraction, while p53 protein accumulation was evaluated immunohistochemically using the monoclonal anti-p53 antibody, CO7. Biomarkers were correlated with clinico-pathologic findings and survival by univariate and multivariate analysis. p53 protein was found in 40 tumors (50%), and was associated with significantly reduced overall survival. In patients with immunopositive tumors, depth of primary tumor invasion, lymph-node status. TNM stage and tumor grade were also significant prognostic factors. Additional predictors of reduced overall survival after esophagectomy, determined by flow cytometry, included S-phase fraction above 10%, aneuploidy (DNA index 1.2-1.8) and multiploidy (DNA index > 2.2). This study further implicates p53 in the pathogenesis of esophageal squamous-cell carcinoma. Prognostic factors such as p53 protein, S-phase fraction and DNA index may be useful in stratifying patients for adjuvant therapies in future clinical trials of esophageal cancer.