Effect of 5 years of CT-scan and CEA follow-up on survival endpoints in patients with colorectal cancer: the PRODIGE-13 FFCD phase III trial.

[BACKGROUND] Intensive follow-up of patients after curative surgery for colorectal cancer is recommended by various scientific societies. However, these recommendations are based mainly on expert opinions, while the results of the few clinical trials are controversial. Moreover, no survival benefit has been demonstrated to date.

[PATIENTS AND METHODS] PRODIGE-13 is a cooperative prospective multicentre controlled phase III trial evaluating by factorial plan the impact of (i) intensive radiological monitoring [alternating abdominal ultrasound (US)/computed tomography (CT) scan/3 months] versus standard monitoring (US/3 months and thoracic radiography/6 months) and (ii) carcinoembryonic antigen (CEA) assessment versus no assessment, in the follow-up of resected stage II or III colorectal cancer with no evidence of residual disease on baseline postsurgical investigation in France and Belgium. The primary endpoint was 5-year overall survival (OS).

[RESULTS] Altogether, 2009 patients were randomly assigned. Among them, 16% had rectal cancer, and 44% left colon cancer; 75.9% were <75 years old. With a median follow-up of 7.8 years, cancer recurred in 22.3% of patients (local 10.5%, metastatic 72.9%, both 16.6%). The 5-year OS rates were 82.1% [95% confidence interval (CI) 78.5% to 85.2%] in group A (intensive imaging + CEA) versus 84.1% (95% CI 80.5% to 87.0%) in group B (intensive imaging alone), versus 83.6% (95% CI 80.1% to 86.6%) in group C (standard imaging + CEA) versus 79.5% (95% CI 75.7% to 82.8%) in group D (standard imaging alone) [P (log-rank) = 0.170]. Median OS was not reached in the four groups. Five-year relapse-free survival (RFS) was 73.8% in the CT-scan surveillance group versus 69.3% in the no-CT-scan group [hazard ratio (HR) 0.89, 95% CI 0.76-1.03, P = 0.108]. Five-year RFS was 71.3% in the CEA surveillance group versus 71.8% in the no-CEA group (HR 1.00, 95% CI 0.86-1.16, P = 0.959).

[CONCLUSIONS] Among patients with stage II or III colorectal cancer, after curative surgery, the implementation of CEA and/or CT-scan surveillance did not provide any benefit in 5-year OS for the overall population of the study.