BERKELEY, CA (UroToday.com) - We investigated the anatomical localization of the draining lymph nodes (LNs) of the lateral bladder wall by preoperatively injecting a radiopharmaceutical into the lateral, non-tumor-bearing bladder wall of 40 consecutive cystectomy patients with bladder cancer (cT1-3, cN0, cM0) located in a single bladder hemisphere.[1] We used preoperative 3D-fusion of single photon emission-computed tomography (SPECT) and computed tomography (CT) for the detection and localization of radioactive nodes. Intraoperatively, the presence of radioactive LNs was confirmed by a handheld gamma-probe. Radioactive LNs were separately resected before performing an extended pelvic back-up lymphadenectomy.
We thus detected a total of 228 radioactive LNs in 40 patients. The number of detected radioactive LNs highly varied from patient to patient (median: 6 LNs per patient; range: 1-17), confirming the more complex lymphatic pattern in the pelvis compared to e.g. the lymphatic drainage seen in breast cancer. 90% of all radioactive LNs were located within the small pelvis. We found only 10% of radioactive LNs cephalad to the uretero-iliac vessel crossing. However, in all patients with these so called ‘extrapelvic’ radioactive LNs, at least one additional radioactive LN could be found in the external iliac, internal iliac or obturator fossa region.
From the lateral bladder the lymphatic drainage led to all areas of the pelvis: internal, external, and common iliac as well as to the obturator fossa. 15% of the 228 radioactive lymph nodes were found on the contralateral side of the injection. It is noteworthy that 40% of patients had at least one such node. This is in line with the finding of other publications[2,3] which found that contralateral LN metastases in lateralized bladder tumors occur in up to 41% of patients. However, we could not demonstrate any contralateral lymphatic drainage into the internal iliac region. Together with the fact that only very few LNs were found in the so called presacral region and the aortic bifurcation (<3%), this finding is of utmost importance since autonomic nerves and the pelvic plexus are in close proximity. Unnecessary damage to these nerves on the non-tumor bearing side must and can be avoided in order to preserve postoperative sexual and defecatory function. Moreover, it may improve urinary continence in patients who undergo ileal bladder substitution because the tonus at rest of the membranous urethra is regulated by sympathetic nerves. According to our mapping study, preservation of LNs along the dorsomedial contralateral bladder pedicle should not compromise tumor radicality in strictly laterally located bladder cancer.
Figure 1. Single-photon emission computed tomography (SPECT; top left) and fused sagittal (top right), transverse (bottom left), and coronal (bottom right) SPECT-CT images showing a radioactive node of the right external iliac region close to the right iliac bifurcation as well as radioactivity of the right lateral bladder wall (injection site)
References:
- Roth B, Zehnder P, Birkhäuser FD, Burkhard FC, Thalmann GN, Studer UE. Is bilateral extended pelvic lymphadenectomy necessary for strictly unilateral invasive bladder cancer? J Urol. 2012; 187: 1577.
- Mills RD, Turner WH, Fleischmann A et al. Pelvic lymph node metastases from bladder cancer: outcome in 83 patients after radical cystectomy and pelvic lymphadenectomy. J Urol 2001; 166: 19.
- Leissner J, Ghoneim MA, Abol-Enein H et al. Extended radical lymphadenectomy in patients with urothelial bladder cancer: results of a prospective multicenter study. J Urol 2004; 171: 139.
Written by:
Beat Roth, MD, et al. as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Staff Member of the Urology Department
University of Bern
Switzerland
Postdoctoral Fellow
Urology Department
MD Anderson Cancer Center
Houston, TX USA
More Information about Beyond the Abstract