Elective Lymph Node Dissections - Still a Standard in Cancer Surgery?

Purpose: Since more than a century elective radical dissection of regional lymph nodes is a standard procedure in tumour surgery. We discuss whether or not this standard is still up to date. Methods: The discussion was based on evaluations from well known clinical trials and cohort studies as well as from the results of the Munich Cancer Registry (MCR). Results: Distant metastases develop extravasally from disseminated tumour cells that originate from the primary tumour. Therefore, three categories of metastases can be described: First, regional lymph node metastases treated by surgical and/or adjuvant therapy or by watchful waiting. Although the number of positive lymph nodes is one of the most important prognostic factor in all cancer sites, treatment of lymph nodes does not affect long-term survival. The number of positive lymph nodes is therefore simply a marker, but not a cause, of distant metastases. This seems to be generally valid. Also, the major part of local recurrences can be seen as local metastases. The frequency of local relapse can be influenced by surgery, adjuvant treatment or radiotherapy only with a small impact on survival. Distant metastases normally determine the course of disease. Whether metastases can be a source of new clinically relevant metastases that influence the prognosis has to be questioned by the presented analyses of tumour growth times. Conclusions: The gene-based control of metastases implies a principal process of metastatic spread for solid tumours. The hypothesis metastases do not metastasise has a high plausibility. Reduction of lymph node dissection and its performance only in those cases where it is necessary for treatment decisions seems to be (bio)-logically consequent.