Increase of serum CA19-9 level without an evident lesion on conventional imaging is insufficient for justification of ¹⁸FDG-PET examination

Background/Aims: The serum tumor marker carbohydrate associated antigen 19-9 (CA19-9) has been used for screening for cancer, because its increase has been associated with many cancers. We aimed to evaluate the clinical value of positron emission tomography using F-18 fluorodeoxyglucose (¹⁸FDG- PET) that was prompted by increases of serum CA19-9 without findings on conventional imaging. Methodology: Twenty-two patients were retrospectively selected. Eleven were without a history of cancer and eleven had a history of cancer and were treated with curative intent. All ¹⁸FDG-PET findings were compared with the findings of histopathology by surgery or biopsy, or clinical follow-up for at least 1 year. Results: We found only two true positive cases, and eleven cases without a cancer history included 10 true negatives and one false positive. Conclusions: Increases in serum CA19-9 are caused by many benign conditions. Increases of CA19-9 without findings on conventional imaging do not justify ¹⁸FDG-PET examination, particularly in patients without a cancer history.