Editorial Comment to Advances in sentinel node dissection in prostate cancer from a technical perspective.

Abstract

Pelvic lymphadenectomy is still the gold standard for lymph node staging in prostate cancer. The lymph node status is not only of prognostic relevance, but also of tremendous therapeutic (e.g. adjuvant or salvage therapy) relevance in prostate cancer. The role of pelvic lymphadenectomy as a therapeutic intervention has been the focus of renewed interest, especially in patients with minimal lymphatic dissemination. There is general consensus that extended pelvic lymphadenectomy achieves the highest accuracy for lymph node staging in prostate cancer. However, the staging benefit of extended (pelvic) lymphadenectomy is accompanied by the potential risk of morbidity. Therefore, sentinel guided lymphadenectomy has replaced extended lymphadenectomy in several tumors. In 1999, Wawroschek et al. started to transfer techniques and concepts of sentinel node identification in other tumor entities to prostate cancer.1 Further studies could show a high staging accuracy and a low morbidity of radioistotope-guided sentinel lymphadenectomy.2 In a recent study, more lymph node-positive patients were detected by sentinel lymphadenectomy than expected from the European guideline nomogram or other extended lymphadenectomy series. Presently, different new (hybrid) tracers, such as the near-infrared fluorescent dye indocyanine green in connection with robotic, laparoscopic and open radical prostatectomies, and magnetic nanoparticles are being tested for marking and intraoperative detection of sentinel lymph nodes in prostate cancer.3 Acar et al. have well summarized this evolution, clinical applications and the latest technical developments of the sentinel concept in prostate cancer.4 The pros and limitations of the sentinel approach, and the various options for sentinel marking and detection, were viewed extensively. The authors emphasized that the detection of sentinel lymph nodes outside the extended lymphadenectomy template has the potential to improve nodal staging in prostate cancer. As such, the possibility of an extended pelvic lymphadenectomy overlooking a part of the lymph node metastases, possibly in the pre-sacral region, is overcome by being able to detect it through the sentinel lymphadenectomy. Joniau et al. did not detect 13% of metastatic lymph nodes by applying only an extended lymphadenectomy.5 On the other side, the sentinel concept is also subject to limitations. One problem with this technique is that when lymph nodes are fully metastasized or lymph pathways are blocked, the afferent lymph will be directed to other lymph nodes/non-sentinel lymph nodes.6 These nodes will not be positive on sentinel lymph node imaging, resulting in false negative findings. If the goal in such cases is to remove all pelvic lymph node metastases, high-risk patients have the option of undergoing a combination of sentinel guided and extended lymphadenectomy. For these reasons, the authors suggest that extended pelvic lymph node dissection is still required in conjunction with sentinel lymphadenectomy. However, this also means an overtreatment for many patients. In addition, the targeted sentinel lymphadenectomy offers the advantage that only a few lymph nodes have to be examined histopathologically. This provides the opportunity to examine these lymph nodes more intensely or to increase the detection especially of small lymph node metastases. Despite these aforementioned issues, the high sensitivity of sentinel-guided lymphadenectomy, the opportunity of integration in the robotic approach, and the promising results of studies with new and radiation-free tracers that can be used by a urologist alone, speak clearly to the future viability of sentinel technology in prostate cancer patients. None declared.