Low efficacy of serum levels of CA 19-9 in prediction of malignant diseases in asymptomatic population in Taiwan

BACKGROUND/AIMS: Serum levels of carbohydrate antigen (CA) 19-9 have long been employed as a biomarker in diagnosing pancreatic cancer in symptomatic patients. We assessed the clinical usefulness of serum CA 19-9 in screening pancreatic cancer and other malignancies in individuals without symptoms. METHODOLOGY: The study enrolled 5,343 consecutive asymptomatic individuals who completed a health check-up comprising serum CA 19-9, chest film, abdominal ultrasonography, esophagogastroduodenoscopy, and colonoscopy or sigmoidoscopy. The sensitivity, specificity and positive predictive rate of CA 19-9 in detecting cancers were analyzed. RESULTS: There were 385 patients (7.2%) with CA 19-9 higher than 37 U/mL. Two patients diagnosed with pancreatic cancer had CA 19-9 levels of 46,885 U/mL and 88.4 U/mL, respectively. Thirteen among 58 patients with other cancers had CA 19-9 levels higher than 37 U/mL. If the cut-off value of CA 19-9 was set at 37 U/mL, the sensitivity and specificity for pancreatic cancer and other cancers were 100% and 92.8%, as well as 22.4% and 92.9%, respectively. However, the positive predictive rates for pancreatic cancer and other cancers were as low as 0.5% and 3.4%, respectively. CONCLUSIONS: Efficacy of CA 19-9 in predicting either pancreatic cancer or other cancers in the asymptomatic population is low.