Wide facility-level variation exists in the extent of pelvic lymph node dissection (PLND) during radical prostatectomy in men with high-risk prostate cancer (PCa) despite lack of an apparent survival benefit associated with more extensive PLND, according to a recently published study.
Using the National Cancer Data Base, David F. Friedlander, MD, MPH, of the University of California San Diego, and colleagues studied 13,652 men with a high predicted probability of 10-year survival and who underwent radical prostatectomy. Of these, 11,284 (82.7%) had no/limited PLND (0-9 lymph nodes), 1601 (11.7%) had received a standard PLND (10-16 lymph nodes), and 767 (5.6%) underwent extended PLND (17 or more lymph nodes).
Compared with standard PLND and no/limited PLND, extended PLND was not significantly associated with improved survival at a median follow-up of 83.3 months, Dr Friedlander’s group reported in Annals of Surgical Oncology.
The risk adjusted facility-level predicted probabilities of no/limited, standard, or extended PLND ranged from 17.8% to 96.3%, 3.3% to 53.3%, and 0.01% to 52.6%, respectively. “To our knowledge, our paper is the first to demonstrate facility-level variation in predicted probabilities of various PLND extents, with most facilities favoring no/limited PLND,” the authors wrote.
The finding is striking, they noted, given that American Urological Association guidelines recommend PLND for patients with intermediate- or high-risk disease and European Association of Urology guidelines recommend extended PLND in high-risk cases.
The finding of no survival benefit with more extensive PLND is consistent with prior research. “Our follow-up could have been longer, ideally, but, at the end of the day, we did find that despite this variation, there really is no difference in overall survival with different extents of pelvic lymph node dissection,” Dr Friedlander told Renal & Urology News.
Academic medical centers were more likely than other types of facilities to perform extended PLND. These centers tend to have greater interdisciplinary collaboration and may have tumor boards and the presence of multiple specialties, he explained. “As a result,” he said, “specialists may be able to collaborate with one another, either preoperatively or postoperatively, and discuss contemporary literature guiding clinical and surgical practice, including the performance of pelvic lymphadenectomy.”
R. Jeffrey Karnes, MD, Chair of the Division of Community Urology at the Mayo Clinic in Rochester, Minnesota, who was not involved in the new study but has conducted research on PLND during radical prostatectomy, commented that “latent variables are at play” that might influence how PLND extent is interpreted, such as how surgeons submit lymph nodes for pathologic examination. For example, if nodes are submitted in packets based on where they were removed (such as from right external iliac vs right pelvic regions), the former may result in a larger node count, he said.
In addition, there might be inter- and intra-pathologic variations in how nodes are counted. Further, Dr Karnes pointed out that the number of nodes removed does not necessarily correlate with PLND extent, which is related more to regions of dissection. For example, surgeons could remove a lot of nodes from the external iliac region yet miss critical areas (such as near the internal/hypogastric region), he said, adding that there are mapping studies for PLND in prostate cancer that highlight critical areas to dissect.
Dr Karnes also said he is unclear how the investigators came up with the number of nodes that defined extended vs standard dissection. Although they performed a sensitivity analysis, they did not present the numbers used to establish the cut points. They also did not determine if the number of nodes removed resulted in a higher rate of detecting positive nodes.