Steep Learning Curve for Robot-Assisted Prostatectomy

Only for high-volume centers?

Nick Mulcahy

February 18, 2011

February 18, 2011 — There is a sharp learning curve with robotic-assisted laparoscopic radical prostatectomy (RALP). Surgeons only reached "expert-level" results after undertaking more than 1600 prostate cancer surgeries, according to a new retrospective study with a very small sample of surgeons.

A positive surgical margin rate of less than 10% — a standard goal for prostatectomy — was the measure used to signify high-level competence, said lead author Prasanna Sooriakumaran, MD, PhD, from Cornell University in New York City.

"A long learning curve must be overcome in order to optimize results for the patient," said Dr. Sooriakumaran. He spoke at a press conference ahead of the 2011 Genitourinary Cancers Symposium, where the study will be presented.

Competence and excellence with RALP are 2 different things, said Dr. Sooriakumaran.

"The learning curve, with regard to safety in performing the procedure, has been reported to be around 25 to 40 cases," he said.

However, there is "no good evidence as to how long it takes to achieve expert-level results for RALP," he added; this was the impetus for the study.

Given the study's findings, Dr. Sooriakumaran noted that RALP is "not as easy as the manufacturers make it out to be."

"These data will make everyone pause," said Nicholas Vogelzang, MD, from US Oncology, who moderated the press conference.

"Expertise comes with greater and greater amounts of experience," said Dr. Vogelzang. He pointed out that "the same thing holds for open radical prostatectomy."

The study has a very notable limitation — it looked at the RALP surgical outcomes of only 3 urologists: 1 from the University of Pennsylvania in Philadelphia; 1 from the Karolinska Institute in Stockholm, Sweden; and 1 from Cornell University. However, the trio had a lot of procedures under their belts. The study was undertaken using the surgical results of 3794 RALP patients over a 6-year period between 2003 and 2009.

Only at Centers of Excellence?

According to Dr. Sooriakumaran, 90,000 radical prostatectomies are performed annually in the United States. Of those, more than 70,000 are done with RALP, and a majority of RALP procedures are performed by surgeons who do fewer than 100 cases a year, he noted.

These numbers are partly explained by the fact that surgical robots have increased "exponentially" in the United States, Dr. Sooriakumaran explained.

"Robotic prostatectomy is gaining in popularity and being done by a large number of surgeons who thus do relatively few cases," he noted.

However, RALP is "not a simple procedure to do," said Dr. Sooriakumaran, in part because there is "no tactile feedback," something other surgeons use to help determine the presence of cancer in the organ. Because of the long learning curve with RALP, Dr. Sooriakumaran proposed that the procedure not be done at small-volume community hospitals but instead be largely performed at "high-volume centers of excellence."

Something akin to this proposal has already occurred in Las Vegas, Nevada, said Dr. Vogelzang. Of the 45 or so urologists in the city, only 4 or 5 are doing robotic prostatectomies, he said. "They decided among themselves who will do these surgeries."

Length of Operation Evaluated Too

In addition to determining the mean overall positive surgical margin rates for the 3 surgeons, the study authors examined operative time as a "marker of expertise." They evaluated operation lengths for each surgeon at intervals of 50 operations.

They found that RALPs take more than 3 hours initially, but drop to about 2 hours after approximately 750 procedures. Interestingly, the operative time eventually increases again; after about 1500 procedures, it approaches 2.5 hours or more.

The study also included an analysis of a subset of patients with extracapsular involvement. In these more difficult cases, the positive-margin rate hovered around 40% for the entire study period. This was expected, said Dr. Sooriakumaran, because in these cases, the cancer had already spread beyond the prostate.

One of the coauthors, Ashutosh Tewari, MD, reports receiving research funding from Intuitive Surgical. Dr. Vogelzang reports a leadership position at US Oncology; serving as a consultant for Amgen, Aveo, Bayer, Celgene, Dendreon, Eisai, GE Healthcare, Genentech, GlaxoSmithKline, Medscape, Novartis, Pfizer, Sanofi-Aventis, and Wilex; and receiving honoraria from Amgen, ArQule, Bayer, Clinical Care Options, Cougar Biotechnology, Genentech, Imedex, Lilly Lippincott, Williams and Wilkins, Medscape, Novartis, Onyx, Pfizer, and Veridex.

2011 Genitourinary Cancers Symposium (GUCS). February 17, 2011.

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