Modeling recurrence in colorectal cancer

Objective: To assess the role of recurrence in prognosis of colon cancer, we investigated several methodologic issues, including application of classic survival analysis and Markov model. Study Design and Setting: The data were recorded by the Registry of Digestive Tumors of Cote d'Or, France, for 874 patients who had been treated by surgery between 1976 and 1984 and followed for up to I 1 years. Survival analyses included the Cox proportional hazards model and its two generalizations that allow recurrence to be taken into account as a time-dependent covariate or as a competing outcome. The Markov model was used to analyze simultaneously recurrence and death. Results: The competing risks approach is not appropriate because censoring is indisputably informative. The Markov model and the Cox model. with recurrence as a time-dependent covariate, provided similar results, demonstrating the impact of age and gender on recurrence and revealing a reduction in the effect of site and stage on mortality. Conclusion: A Markov multistate model seems to give new insights about the course of digestive cancer progression and into the role of recurrence in this process. (C) 2004 Elsevier Inc. All rights reserved.