Preoperative staging of cervical cancer: Is FDG PET/CT really effective in patients with Ib1 stage?

Objectives To evaluate a) the role of FDG PET/CT in preoperative assessment of N-staging in Ib1 cervix cancer patients (pts); b) the correlation between the metabolic characteristics of cervical tumor uptake and the presence of lymph-node (LN) metastases.

Methods Fifty-six pts (mean age: 47 yrs) with FIGO stage Ib1 cervical cancer underwent preoperative PET/CT study followed by total hysterectomy with bilateral salpingo-oophorectomy and systematic pelvic lymphadenectomy. Total LNs dissected were 1593 (mean per pt: 28 LNs). PET/CT images were retrospectively analysed and correlated to histopathological findings. Maximal and mean standardized uptake value (SUV max, SUV mean), metabolic tumor volume (MTV), total lesion glycolysis (TLG) of cervical uptake were considered and calculated by PETVCAR software on Adwantage GE workstation.

Results PET/CT detected 45/56 (80%) primary tumor; the remaining 11 pts with no pathological cervical uptake were all previously submitted to conization. PET/CT resulted negative at pelvic LN level in 54/56 pts: 47/54 truly negative, 7/54 falsely negative. In the remaining 2/56 pts PET/CT was true positive in 1 pt and false positive in the other. On patient-based analysis, sensitivity, specificity, accuracy, negative and positive predictive value of PET/CT in detecting pelvic LN metastases were respectively 13%, 98%, 86%, 87% and 50%. There were no significant correlations between the presence of LN metastases and respectively SUVmax (p=0.18), SUVmean (p=0.09), MTV (p=0.29), TLG (p=0.58) of the primary tumor.

Conclusions In the preoperative staging of 1b1 cervix cancer: a) FDG PET/CT should not be recommended because of its low diagnostic accuracy in N-staging; b) cervical tumor FDG uptake is not significantly correlated to LN metastatic involvement