Effect of 5 years of CT-scan and CEA follow-up on survival endpoints in patients with colorectal cancer

Abstract

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)/CT-scan/3m) versus standard monitoring (US/3m and thoracic radiography/6m) 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 post-surgical investigation in France and Belgium. The primary endpoint was 5-year overall survival (OS).

Results: Altogether, 2009 patients were randomized. Among them, 16% had rectal cancer, and 44% left colon cancer; 75.9% were less than 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%CI [78.5;85.2]) in group A (intensive imaging + CEA) vs. 84.1% (95%CI [80.5;87.0]) in group B (intensive imaging alone), vs. 83.6%, (95%CI [80.1;86.6]) in group C (standard imaging+ CEA) vs. 79.5% (95%CI [75.7;82.8]) in group D (standard imaging alone) (p(logrank)= 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 vs. 69.3% in the no-CT-scan group (HR 0.89 [0.76;1.03]; p=0.108). Five-year RFS was 71.3% in the CEA surveillance group vs. 71.8% in the no-CEA group (HR 1.00 [0.86;1.16]; 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 overall survival for the overall population of the study.

Keywords: CT-scan; Carcinoembryonic Antigen (CEA); colorectal cancer; overall survival; recurrence; surveillance.