Usefulness of Carbohydrate Antigen 19-9 Test in Healthy People and Necessity of Medical Follow-up in Individuals with Elevated Carbohydrate Antigen 19-9 Level

BACKGROUND: Carbohydrate antigen 19-9 (CA 19-9) is a tumor marker whose level is elevated in many types of cancers and other benign conditions. CA 19-9 levels are frequently found to be elevated in individuals during general health examinations. This study aimed to investigate the clinical characteristics of such individuals and to determine the need for medical follow-up. METHODS: We investigated individuals who underwent a health inspection, including a serum CA 19-9 test, at our center. Their CA 19-9 levels, age, sex, body mass index (BMI), and personal and past histories were investigated. Additionally, subgroup analyses were performed for those who underwent follow-up study for the elevated CA 19-9 levels. RESULTS: Of 58,498 subjects, 581 (1.0%) had elevated CA 19-9 levels. Multivariate analyses revealed that older age, female sex, lower BMI, and diabetes were independent predisposing factors for elevated CA 19-9 level. A subgroup analysis revealed that the causative conditions were identified in 129 of 351 subjects (36.8%). Among them, the causative conditions in 31 subjects (8.8%, including four cases of cancer and 15 of benign tumors) were not detected at the initial check-up and were found during the follow-up period. CONCLUSION: The use of CA 19-9 as a marker for cancer in healthy individuals is inappropriate. However, medical follow-up in individuals with elevated CA 19-9 levels may be useful because some causative diseases may be detected during follow-up.