S100A6 EXPRESSION IN PANCREATIC CANCER: A NOVEL PROGNOSTIC MARKER.:

Introduction: Pancreatic cancer is a devastating disease, responsible for over 6,000 deaths in the UK each year. By analysing the protein content of pancreatic cancer, we have previously demonstrated increased expression of a calcium binding protein, S100A6. We investigated the prognostic significance of S100A6 expression in pancreatic cancer compared with other clinical and pathological parameters. Methods: We performed immunohistochemical analysis of a tissue microarray, containing over 280 samples of benign and malignant pancreatic tissue. The intensity of staining for each specimen was categorised into high and low expression. We first determined if there was any association between S100A6 expression and other pathological and molecular parameters. Univariate and multivariate analyses were then performed on all investigated parameters. Results: High S100A6 expression was observed in 40 (80%) of 60 malignant cases and only 12 (28) of 43 benign samples (p<0.0001). We found no significant association between S100A6 expression and other clinical or pathological factors. Univariate analysis revealed a significantly decreased survival time in high S100A6 expressing cases (p=0.01), positive nodal metastases (p=0.04) and resection margin involvement (p=0.05). When analysed in a multivariate regression model, only S100A6 emerged as an independent factor (p=0.003). Conclusions: S100A6 expression represents a significant prognostic marker in patients undergoing resection for pancreatic cancer. We found it to be superior to other pathological parameters such as lymph node status and tumour differentiation. Its role in pancreatic cancer is at present unknown, however, the findings of this study clearly merit further investigation.