Application of FDG-PET for detection of malignant lesions in patients with increasing blood tumor markers but without a malignant history

Objectives To evaluate the clinical application of FDG-PET imaging for detection of malignant lesions in patients with increasing levels of blood tumor markers but without a history of malignancy.

Methods FDG-PET was used to examine 132 patients with increasing levels of blood tumor markers but without a history of malignancy. The results of FDG-PET and conventional workup (CWU) were compared. The final diagnosis was based on the pathological evidence, other medical imaging results and follow-up.

Results There were 61 patients with malignant lesions and 71 without. In FDG-PET imaging, the SUVmax of the major lesion in malignant (n=61) and benign patients (n=35) was not significantly related to the increased level of tumor markers (r=0.10, p<0.05). The diagnostic sensitivity, specificity, accuracy, positive predictive value and negative predictive value of FDG-PET for malignant patients were 95.1, 83.1, 88.6, 82.9 and 95.2%, respectively. Sixty-one (100%) true-positive patients were found by CWU and no statistically significant differences in sensitivity were observed between FDG-PET and CWU (p>0.05). Thirty-six healthy subjects without findings on CWU were also without abnormal FDG accumulation on FDG PET imaging.

Conclusions FDG-PET imaging is valuable for the detection of malignant lesions in patients with increasing levels of blood tumor markers but without a history of malignancy. It is reasonable to use FDG-PET imaging in situations in which the results of CWU were uncertain.