Lymph node staging in prostatic carcinoma revisited

Abstract

Despite presumed curative operation almost one-third of patients with prostatic carcinoma relapse. One obvious reason is that the preoperative lymph node staging is not sufficiently effective. Imaging modalities (CT and NMR) have not resolved the problem. Presently lymphadenectomy is not recommended in patients with Gleason score <7 and PSA <20 ng/ml owing to the low frequency of positive nodes. However, these data are based on experience with limited dissection. Results from extended dissection reveal a higher rate of metastases than previously found. The results from extended dissections showed that more than half of the diagnosed lymph node metastases were found outside the generally recommended regions. The drawback is the higher complication rate that follows. Thus the staging can be improved but if this translates into a survival benefit it needs to be addressed in controlled trials. Alternative techniques for lymph node staging have recently been developed. The sentinel lymph node (SLN) method has been tested and proved feasible. The results corroborated those of extended dissection, namely that the obturator region is insufficient to reflect the field of metastases. High-resolution MRI with magnetic nanoparticles can detect small and otherwise undetectable lymph-node metastases. Positron emission tomography (PET), using acetate or choline as tracers, has performed better than fluoro-2-deoyglucose for detection of relapsing prostate cancer after radical prostatectomy. Studies have also started to assess its role for lymph node staging. In summary, lymph node staging has to cover a larger anatomical field than routinely used. Whether surgical dissection can be replaced by the new imaging modalities is presently under investigation.