Endoscopic screening and determination of p53 and proliferating cell nuclear antigen in esophageal multistage carcinogenesis: a comparative study between high- and low-risk populations in Henan, northern China

The objective of this study was to characterize the histologic changes from endoscopic screening for early esophageal cancer (EC) on subjects at high-incidence area (HIA) and low-incidence area (LIA) in Henan, China, and to further compare the changes in p53 and proliferating cell nuclear antigen (PCNA) in the multistage of human esophageal carcinogenesis from these two populations. The detection rate of basal cell hyperplasia (BCH) and dysplasia (DYS) was higher in the subjects from HIA than in those from LIA. Out of the 1568 symptom-free subjects examined at HIA, 10 (0.6%) cases with early squamous cell carcinoma (SCC) were identified. Immunoreactivity of p53 and PCNA was observed in cell nuclei of esophageal biopsies and surgically resected esophageal cancer specimens both in HIA and LIA. With the lesions progressed from normal epithelium to BCH to DYS to SCC, the positive-immunostaining cells expanded from basal layer to superficial layer, and the number of positive cells/mm2 for p53 and PCNA increased, and was significantly higher in HIA than in LIA among the similar morphological lesions (P < 0.01). The number of p53 positive cells/mm2 in SCC from HIA was almost fivefold higher than SCC from LIA (P < 0.01). The remarkable difference was also observed between HIA and LIA in DYS and BCH. The present results indicate that p53 protein accumulation is an important early biomarker for identifying high-risk subjects for EC.