Complementary Roles of Squamous Cell Carcinoma Antigen and 18F-FDG PET/CT in Suspected Recurrence of Cervical Squamous Cell Cancer

PURPOSE To assess the clinical value of FDG PET/CT and evaluate the complementary roles of serum squamous cell carcinoma antigen (SCCAg) and FDG PET/CT in the diagnosis of suspected recurrent of cervical squamous cell cancer. METHODS Serum SCCAg levels were retrospectively reviewed in patients previously treated for cervical squamous cell carcinoma, who had suspected recurrence of cervical cancer and who had undergone FDG PET/CT scans. The clinical impact of elevated SCCAg (>1.5 ng/ml) and negative SCCAg (≤1.5 ng/ml) levels were analyzed based on the results of PET/CT and final diagnosis. RESULTS The overall patient-based sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of PET/CT for the detection of tumor recurrence or malignancy were 100% (86/86), 80.8% (21/26), 95.5% (107/112), 94.5% (86/91) and 100% (21/21), respectively. Of the 112 patients included in this study, recurrence or malignancy was detected by PET/CT in 62 of the 64 patients with elevated SCCAg, compared to 24 of the 48 patients with negative SCCAg levels. The overall patient-based PPV, NPV, sensitivity and accuracy of SCCAg for the detection of tumor recurrence or malignancy were 96.9% (62/64), 50% (24/48), 72.1% (62/86) and 76.8% (86/112), respectively. The five false-positive PET/CT results were all associated with patients with negative SCCAg levels. The PPV of positive PET/CT-associated elevated SCCAg for the detection of tumor recurrence or malignancy was 100% (62/62). The NPV of negative SCCAg-associated negative PET/CT was 100% (19/19). CONCLUSIONS Serum SCCAg evaluation and FDG PET/CT imaging can be complementary techniques in cases of suspected recurrent cervical squamous cancer. Positive PET/CT with elevated SCCAg can predict recurrence. Although PET/CT cannot confidently be deferred due to a negative SCCAg test, the possibility of a false-positive PET/CT in those cases may have diagnostic importance.