Introduction: The clinical value of established prognostic factors seems to be limited since they fail to predict reliably survival of patients after resection of cholangiocarcinoma. DNA ploidy reflecting irregularities of chromosome number and content might be an alternative predictor. In this study, we evaluated the DNA ploidy as a prognostic factor for survival of patients after resection of cholangiocarcinoma.
Methods: This prospective study included 34 patients with cholangiocarcinoma which were surgically resected and followed up to death or more than 3 years. Tissue specimens were taken from the liver tissue immediately after resection and DNA ploidy determined. Survival was related to the type of DNA ploidy as well as to five established prognostic factors.
Results: Multivariate analysis revealed that in this study only DNA ploidy (P = 0.012) was significantly associated with prediction of survival. In contrast, neither tumor stage pT (P = 0.073) nor tumor grade pG (P = 0.154), resection margins R (P = 0.322), metastasis M (P = 0.060), lymph node stage pN (P = 0.209), age (P = 0.13) nor sex (P = 0.849) could significantly predict survival. Three-year survival was best for patients with diploid tumors (n = 6) of whom 75% survived more than 3 years. Poor prognostic signs associated with short term survival of less than 18 months were tumors classified as aneuploid (n = 17), large tumors pT4 (n = 8), metastasis pM1 (n = 11), undifferentiated tumors pG3 (n = 9) and non-tumor-free resection margins R2 (n = 14). The best predictor for poor prognosis was aneuploidy since it could identify more patients with a fatal outcome than other prognostic factors. DNA ploidy turned out to discriminate highly significant between diploid, polyploid and aneuploid tumors.
Discussion: The most accurate prognostic factor for survival of patients after resection of cholangiocarcinoma was DNA ploidy. Most patients suffering from a diploid tumor turned out to be long term survivors whereas aneuploid tumors indicated a poor prognosis with a rather short survival time of less than 18 months. We conclude that DNA ploidy is a valuable diagnostic tool for identifying subgroups of patients that are at higher risk for tumor progression.