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

Abstract

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.

Figure 1

From the left, axial CT, fused PET/CT, and PET images of a false negative case. PET showed no FDG groin uptake bilaterally, whereas a partial metastasis was found at histology in a left inguino-femoral LN. CT = computed tomography, FDG = fluoro-deoxy-glucose, PET/CT = positron emission tomographic/computed tomographic.

Figure 2

From the left, axial CT, fused PET/CT, and PET images of a false positive case. PET showed a pathological FDG uptake at the right inguinal site (SUV_max 3.53), whereas no metastases were found at histology. CT = computed tomography, FDG = fluoro-deoxy-glucose, PET/CT = positron emission tomographic/computed tomographic.