Sensitivity and specificity of Carcinoembryonic Antigen (CEA) in an intensified colorectal cancer follow-up protocol

Background Carcinoembryonic Antigen (CEA) is a serum tumor marker that fun ctions as an early warning for the presence of recurrent disease (RD) in the follow-up of colorectal cancer (CRC) patients. Objective Aim of this study was to find the sensitivity and specificity of a bimonthly CEA measurement schedule, where a 20% CEA rise was indicative for the presence of RD, during follow-up of patients included in the randomized CEAwatch follow-up trial (Netherlands Trial Register 2182). Patients and Settings Patients with AJCC stage I-III in eleven Dutch hospitals were included after curative resection and followed between October 2010 and October 2012. Design The intervention follow-up schedule consisted of routine bimonthly CEA measurements and yearly routine imaging. The threshold was a 20% rise after two months followed by a confirmative CEA-rise four weeks later. If the threshold was passed, imaging was advised in search for RD. Main outcome measures The sensitivity and specificity of this schedule were calculated based on all patients that had at least two consecutive CEA measurements (n = 1,893). Results RD was detected in 105 patients (5.5%). Median follow-up time was 34 months (range 2–71 months). In 58 patients, the pre-defined consecutive rise was observed. This schedule had a sensitivity of 55% and a specificity of 92% regarding the presence of RD. The sensitivity for this schedule was 68% if only patients with elevated preoperative CEA levels were considered. Limitations Some protocol violation with the intervention follow-up protocol Conclusions The proposed schedule of 20% rise / two months confirmed by further rise after four weeks has an acceptable sensitivity and high specificity and is suitable for use as a first-line screening in follow-up.