Pelvic lymph node distribution and metastases of prostate and bladder cancer: a systematic literature review and template proposal

Purpose To systematically review the relevant literature that evaluates the LN topographical distribution and propose a uniform template. Methods A bibliographic search of PubMed/Medline, Embase and SCOPUS was performed for studies reporting data of LN imaging and/or nodal resection. Results 101 and 26 articles met the inclusion criteria for PCa and BCa, respectively. In PCa, the most common locations of positive LNs for surgical and imaging studies were external iliac (both 38 studies), followed by obturator (38 and 37, respectively). Similarly, in BCa, the most common location of positive nodes for surgical and imaging studies were external iliac (19 and 4, respectively), followed by obturator (15 and 3 studies, respectively). In PCa, median percentages of positive external iliac nodes/patient were 12.2% and 11.6% for surgical and imaging studies, respectively while corresponding rates for BCa were 3.9% and 17.6%. There were high risks of bias across studies as well as high heterogeneity in the definition of the anatomic boundaries of lymphadenectomy templates. Conclusions This review highlights the lack of detailed information on exact LN templates and metastases location, which in turn hinders generation of high-quality evidence on optimal lymphadenectomy templates. Our proposed template is applicable for both imaging and surgical description and could facilitate the translation of anatomical location from imaging to surgical resection.