Complementary Roles of Squamous Cell Carcinoma Antigen and (18)F-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.