Cost-effectiveness of two follow-up strategies for curative resection of colorectal cancer: comparative study using a Markov model.

The follow-up of patients with curative resection of colorectal cancer is still controversial. The means mobilized for postoperative monitoring come at a high cost. However, the modalities are neither formalized nor validated with regard to an improved 5-year survival rate. To compare the cost-effectiveness of both strategies for patient follow-up during the 7 years following curative resection of colorectal cancer, we performed a costeffectiveness analysis adjusted for quality of life. Using data from the literature and a population study, a simulation of follow-up on patients who had undergone curative resection of colorectal cancer was carried out over a 7-year period using a Markov model. Two Markov processes were modeled to compare the cost-effectiveness ratio adjusted for quality of life in patients with a follow-up in accordance with the recommendations of the 1998 French Consensus Conference (standard follow-up) with the carcinoembryonic antigen (CEA) assay and a simplified follow-up. The influence of standard follow-up on the quality-adjusted life expectancy of patients who had Duke's stage A and B colorectal cancer appears to be modest, with increases of 2.5 months and 1.3 months, respectively; it is more acceptable for patients who had had Duke's stage C, with an increase of 11 months. The high variability of cost-effectiveness ratios (> 7 years) of +/- 44,830 and 180,195 Euro per quality-adjusted life-years (QALY), respectively) did not favor the standard follow-up. The cost-effectiveness ratio (> 7 years) of patients having had Duke's stage C colorectal cancer was 1,058 (sd: 2746) Euro per QALY and could favor the standard follow-up. This study showed that standard follow-up with CEA assay tended to preferentially improve the survival of Duke's stage C patients. The type of examination needed and the frequency with which it has to be carried out should take account of the stage, treatment for the initial illness, and the patient's age.