Diagnostic value of serum tumor markers in asymptomatic individuals

Tumor markers, particularly carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP), are widely used in oncology, either in monitoring patients with metastatic colorectal cancer (CEA) or surveillance of hepatocellular carcinoma (HCC/AFP). The objective of this study was to determine the diagnostic value of CEA, CA19-9 or AFP in asymptomatic individuals.

12 asymptomatic individuals (6 males), with age range 55-82 years, referred to outpatient Gastroenterology- Oncology department for second opinion, with slightly elevated serum CEA (8 persons), CA19-9 (2 persons), and AFP (2 persons). The tumor markers were ordered from the primary practitioner or internist in order to avoid further specific examinations, such as colonoscopy. All individuals were totally asymptomatic. One of them had a known-history of 5-year surgically removed malignant pediculated sigmoid polyp and remained asymptomatic since then.

After continuous and repeated meticulous examinations in all individuals, no specific pathology was found to explain the slightly elevated tumor markers. In one male (59 years) and one female (75 years) with slightly elevated CEA levels, 2 small colonic polyps were found, which were endoscopically removed. Repeated CEA levels 3 months later remained borderline high. During follow-up, 3 years after the discovery of slightly elevated tumor markers all individuals remained asymptomatic (positive predictive value / PPV 0%).

Although further prospective studies are necessary, the preliminary results of this study showed that tumor markers are not useful for primary prevention of gastrointestinal malignancy. Moreover, slightly elevated tumor markers are confusing, leading to unnecessary examinations and stress from the individual's point of view.