Combined analysis of p53 and retinoblastoma protein expressions in esophageal cancer

Background. p53 gene mutation and abnormal p53 protein expression, also loss of the retinoblastoma gene and protein expression are frequently associated with esophageal squamous cell carcinoma (ESCC). Recently, the prognostic significance of the combined analysis of p53 protein and retinoblastoma protein (pRB) has been reported in non–small cell lung cancer. However, in ESCC, the prognostic significance of the combined analysis of these proteins remains unclear. In this study, we immunohistochemically analyzed the p53 protein and pRB expressions in surgically resected ESCC, and we evaluated the prognostic significance of the combination of these proteins. Methods. We analyzed p53 protein and pRB expressions immunohistochemically in 191 surgically resected ESCC cases. Overexpression of p53 and loss of pRB were considered abnormal. Results. Overexpression of p53 protein was detected in 79 patients (41%) and decreased pRB nuclear staining occurred in 82 (43%). The Kaplan-Meier survival curve showed that absence of pRB expression was significantly associated with shortened survival (p = 0.001), whereas expression of p53 was not significantly associated with survival. Moreover, p53 and pRB status individually were not independent prognostic factors in multivariate survival analysis. With respect to pRB and p53, the tumors could be grouped into four categories: p53−/pRB+ (31%); p53−/pRB− (27%); p53+/pRB+ (26%); and p53+/pRB− (16%). Favorable prognosis was observed in patients with p53−/pRB+ tumors. Multivariate analysis showed p53−/pRB+ status to be an independent prognostic factor. Conclusions. The combination of p53 protein loss and pRB expression was associated with good prognosis in patients with ESCC.