18F-FDG PET/CT in preoperative staging of vulvar cancer patients: is it really effective?

The aim of this study was to assess the role of 18F-FDG PET/CT in preoperative staging of vulvar cancer patients.29 pts (69 years, range 51-88) with vulvar cancer (clinical apparent stage I-II), underwent preoperative FDG-PET/CT scan followed by radical vulvectomy and bilateral (or monolateral in case of tumor >2 cm from midline) inguinal lymphadenectomy ± sentinel node biopsy. PET/CT images were analyzed in consensus and correlated to histological findings according to a pt-based and a groin-based analyses. SUVmax of the nodal uptake of each inguinal area (if present) was calculated and correlated to histological findings. The presence of distant metastases was also considered and confirmed.PET/CT analysis in consensus resulted negative at the inguinal LN level in 17 pts (10 true negative, 7 false negative) and positive in 12 pts (7 true positive, 5 false positive). Incidence of LN metastases resulted 48%. On pt-based analysis, sensitivity, specificity, accuracy, and negative and positive predictive value of PET/CT in detecting LN metastases were 50%, 67%, 59%, 59%, and 58%, respectively. On a groin-based analysis, considering overall 50 LN-sites, sensitivity, specificity, accuracy, and negative and positive predictive value of PET/CT were 53%, 85%, 73%, 67%, and 76%, respectively. The mean value of SUVmax was 6.1 (range 0.7-16.2) for metastatic nodes, whereas 1.6 (range 0.7 - 5.4) for negative lymph-nodes (P = .007). PET/CT detected pelvic (n = 1) and both pelvic/paraortic (n = 1) nodal metastases.In clinical early stage vulvar cancer FDG PET/CT showed low sensitivity and moderate specificity for N-staging; therefore, it is not an accurate tool for the nodal status assessment. PET/CT may not be cost-effective in detecting the rare event of distant metastases, but further studies are needed.