VAMP-trial: Vulvar cancer Assessment in tumour Margins using intra-operative PET-CT - study protocol.

Background Vulvar cancer is a rare malignancy. Treatment in the early stages consists of a broad excision and sentinel node procedure. Tumour excision stays challenging due to the high risk of local recurrence (43%), which is associated with positive tumour margins. Therefore, a precise method to preserve healthy tissue and detect tumour positive margins intra-operatively, is needed. Direct intra-operative assessment would avoid the need for re-operation and their psychological, technical, and financial consequences. Currently, intra-operative margin assessment can only be done by frozen section, a technique not commonly used due to many disadvantages (i.e. time-consuming, disrupting the workflow and interfering with final assessment). In this study the AURA 10, a submillimetric 3D PET-CT specimen imager, is introduced: a novel approach to assess tumour margins intra-operatively.

Methodology The aim of this open label pilot study is to test the feasibility of using a small PET-CT (the AURA 10) intra-operatively to visualize 18F-FDG-uptake in resected specimens obtained during vulvar surgery. Therefore, one single low-dose intravenous injection of 0.8 MBq/kg 18F-FDG is administered before surgery. The primary objective is to investigate the feasibility of the AURA 10 to detect positive excision margins. The margins on these images will be analysed by the surgeons and compared to the gold standard of sectional histopathological evaluation. The diagnostic performance will be reported in sensitivity, specificity and accuracy. If positive margins are suspected, the surgeon can immediately do a precise re-excision. The secondary objective is to investigate the ability to detect cancer cells in the sentinel lymph nodes. 30 patients will be included with vulvar cancer, vulvar intra-epithelial neoplasia (VIN) or Paget disease, who were eligible for vulvectomy.