Overexpression of podocalyxin-like protein is an independent factor of poor prognosis in colorectal cancer

BACKGROUND: Podocalyxin-like 1 (PODXL) is a cell-adhesion glycoprotein and stem cell marker that has been associated with an aggressive tumour phenotype and poor prognosis in several forms of cancer. In this study, we investigated the prognostic impact of PODXL expression in colorectal cancer (CRC). METHODS: Using tissue microarrays and immunohistochemistry, PODXL expression was evaluated in 536 incident CRC cases from a prospective, population-based cohort study. Kaplan-Meier analysis and Cox proportional hazards modelling were used to assess the impact of PODXL expression on cancer-specific survival (CSS) and overall survival (OS). RESULTS: High PODXL expression was significantly associated with unfavourable clinicopathological characteristics, a shorter CSS (hazard ratio (HR) = 1.98; 95% confidence interval (CI) 1.38-2.84, P < 0.001) and 5-year OS (HR = 1.85; 95% CI 1.29-2.64, P = 0.001); the latter remaining significant in multivariate analysis (HR = 1.52; 95% CI 1.03-2.25, P = 0.036). In addition, in curatively resected stage III (T1-4, N1-2, M0) patients (n = 122) with tumours with high PODXL expression, a significant benefit from adjuvant chemotherapy was demonstrated (p(interaction) = 0.004 for CSS and 0.015 for 5-year OS in multivariate analysis). CONCLUSION: Podocalyxin-like 1 expression is an independent factor of poor prognosis in CRC. Our results also suggest that PODXL may be a useful marker to stratify patients for adjuvant chemotherapy. British Journal of Cancer (2011) 105, 666-672. doi:10.1038/bjc.2011.295 www.bjcancer.com Published online 9 August 2011 (C) 2011 Cancer Research UK