[F¹⁸]-fluoroethylcholine combined in-line PET-CT scan for detection of lymph-node metastasis in high risk prostate cancer patients prior to radical prostatectomy: Preliminary results from a prospective histology-based study

Purpose: To evaluate the diagnostic potential of PET/CT using ([F¹⁸]fluorethylcholine (FEC) for lymph node (LN) staging in high risk prostate cancer (PCa) patients prior to radical prostatectomy (RP). Patients and methods: Twenty patients with localised PCa and ≥20% LN risk according to a published nomogram were prospectively enrolled. FEC PET/CT was done minimum 14 d after prostate biopsy. Afterwards, open RP and extended pelvic LN dissection (ePLND) were performed. Clinical stage, Prostate Specific Antigen (PSA) and biopsy Gleason Grading were assessed and histopathological evaluation of the RP-specimens and dissected LN has been performed. The results from PET/CT were compared with LN metastasis according to their anatomical site. Results: Overall, 285 LN have been removed with a mean number of 15 nodes per patient (7-26). Of the 20 patients, 9 men were LN positive (45%), which corresponds to 31 positive LN with a mean size of 7 mm (0.8-12 mm). Dissection of the obturator fossa, external iliac artery/vein and internal iliac artery/vein revealed 36%, 48% and 16% of positive LN, respectively. FEC PET/CT did not detect one single positive LN, thus was false-negative in 31 metastasis and true negative in 254 LN. Conclusion: Based on our results which confirmed experience from the previous studies, FEC PET/CT scan did not prove to be useful for LN staging in localised PCa prior to treatment and should thus not be applied if clinically occult metastatic disease is suspected.