Low Quality of Evidence for Robot-Assisted Laparoscopic Prostatectomy: A Problem Not Only in the Robotic Literature

By: and ">Markus Graefen

Published online: 01 June 2010

Abstract Full Text Full Text PDF (162 KB)

Refers to article:

Low Quality of Evidence for Robot-Assisted Laparoscopic Prostatectomy: Results of a Systematic Review of the Published Literature eulogo1

Diana C. Kang, Miranda J. Hardee, Susan F. Fesperman, Taryn L. Stoffs and Philipp Dahm

Accepted 14 January 2010

June 2010 (Vol. 57, Issue 6, pages 930 - 937)

The call for standardised and higher quality reports on surgical techniques and outcomes is becoming louder [1]. The reason for this is that the number of low-quality papers is increasing; however, the body of evidence and the knowledge we have about the reported outcomes, unfortunately, is not.

In this issue of European Urology, Kang and coworkers present a systematic review of the literature on robot-assisted laparoscopic prostatectomy (RALP) [2]. They observed that RALP is displacing radical retropubic prostatectomy as the gold standard surgical approach for clinically localised prostate cancer in the United States and is also being used increasingly in Europe and in other parts in the world. One would expect that this remarkable change in treatment pattern with its significant financial implications would be based on evidence of the superiority of RALP. However, having performed an extensive literature search and a thorough evaluation of each retrieved paper, the authors conclude this is not the case.

Two important aspects in this review need to be considered separately. First, the authors state that the published literature on RALP is limited to observational studies of mostly low methodological quality, and they question to what extent valid conclusions about the relative superiority of RALP compared with other existing approaches can be drawn at all. Second, and just as important, they question whether the published results on oncologic and functional outcomes could be generalised to a broader community. The vast majority of the published papers on RALP are authored by a small number of very high-volume surgeons, and I am convinced that the excellent outcomes reported do not derive from use of the robot but from surgeons who are experienced and specialised [3] and [4]. When outcomes in these series are compared with outcome reports of equivalently experienced groups that use different surgical techniques such as conventional laparoscopy or an open retropubic approach, there is no difference [5], [6], and [7]. All objective reviews in this field have concluded that it is the surgical experience that matters, not the instruments used [8].

The urologic literature needs papers like the current review of Kang et al. [2]. The treatment of prostate cancer has become an important market, and it is therefore not surprising that the dramatic change in treatment pattern is obviously not based on a striking improvement of the quality given to a cancer patient but rather on a remarkable marketing campaign. This is what many urologists believe intuitively; however, papers like this offer a solid evidence-based foundation for their opinions.

RALP is a technique that is here to stay. Although I consider myself a protagonist of open radical prostatectomy (RP), I am convinced that the prospects for robotic surgery are amazing, fascinating, and definitely superior to the improvements that can be expected in open surgery. There is already a prototype of the robot at hand that allows a single-port approach, and it is just a matter of a few years until further minimisation of the instruments, integration of imaging techniques, and development of haptic feedback will begin a new era in surgery. Therefore, despite all the problems about a meaningful evaluation in the literature on the pros and cons of robotic surgery, the train is running and nothing will stop it. This is certainly not a very scientific way of introducing new therapeutic approaches; however, this is how changes happen, and despite all reservations, it is the only way that allows quick development.

Kang and coauthors focused on the robotic literature and found that the vast majority of published papers are of low methodological quality. However, I do not think this problem is unique to the robotic literature because methodological problems in reports of surgical procedures can be found regardless of the surgical approach used for RP [1]. However, time will lead to a better estimation of both the advantages and the downsides of a specific surgical approach. Because a lot of time has passed since Patrick Walsh introduced the anatomic approach to open RP, the urologic community has learned that functional outcomes definitely differ between various groups. Montorsi et al showed in a prospective randomised multicentre double-blind trial that 1 yr after surgery, postoperative International Index of Erectile Function scores returned to close to the preoperative value in between 47.8% and 54.2% of patients [9]. In a single-centre series in which only surgeons with >1000 RPs were considered, the same end point was reached by 59% of the patients who had a comparable preoperative situation to those men included in the study by Montorsi et al. [9]. Such studies show there is a difference when more or less experienced surgeons do the procedure. Interestingly, these data on postoperative potency rates seem lower than those published some time ago when open anatomic RP was new. In their initial reports, Walsh and coworkers reported on potency rates in young patients with bilateral nerve-sparing RP as about 90% [10]. There are always slight differences in how potency is defined; however, this is an example of a typical phenomenon in the medical literature: After enthusiastic initial reports, more down-to-earth results eventually show up, giving us a more realistic estimate of what we can expect.

The difference between the literature in open and robotic RP is that the robotic literature is fairly immature, as usual when new techniques are embraced. It always takes some time until downsides are recognised and reported, and this development that took place for open and laparoscopic series is now happening in the robotic literature. A recent collaborative review article by Murphy and coworkers [11] and the review by Kang et al. [2] both demonstrate this evolution in the reports on robotic surgery. One of the downsides of RALP highlighted by Murphy et al. [11] is the fact that the learning curve seems to be far wider than previously reported, and they suggest that >80 cases need to be performed to achieve acceptable results. In my opinion, this is still a optimistic estimate, and I am sure we will eventually see papers like that from Vickers and coworkers in which cancer control rates were correlated to surgical experience measured by the number of open RPs performed by each surgeon [12]. The learning curve for prostate cancer recurrence was steep and did not start to plateau until a surgeon had completed approximately 250 prior operations. The predicted probabilities of recurrence at 5 yr were 17.9% for patients treated by surgeons with 10 prior operations and 10.7% for patients treated by surgeons with 250 prior operations (difference: 7.2%; p<0.001). This aspect is certainly not yet investigated in the robotic literature.

Another important aspect was recently addressed by Bolenz and coworkers, who presented a detailed cost analysis of the various surgical approaches for RP [13]. They showed that RALP is by far the most expensive surgical approach “on the market.” The authors calculated additional costs of $2315 for each case done with the robot, but this total still does not reflect “real-life urology” because the purchase costs ($1.5–1.75 million) and the maintenance fees ($112 000–150 000 per year) were not included. Bolenz et al stated that including these costs would add another $2698 per case. Murphy et al estimated that the use of the robot adds €1500 to the costs of the conventional procedure [11]. Even though cost analyses differ from hospital to hospital and between health systems, the fact that RALP is extraordinarily more expensive than open RP will not change, regardless of how the calculations are done.

Comparing the literature on RALP with the literature of all other surgical approaches, one gets the impression that the robotic literature quite often raises unrealistic expectations and that the results are abused for marketing purposes. Mulhall and coworkers showed that many Web sites advertise RALP with the promise of better potency and urinary continence rates (usually without having their own data) [14]. A recently published paper in JAMA, however, reported that patients who underwent RALP had a worse functional outcome compared with open RP [15]. Furthermore, Schroeck and coworkers showed that the likelihood of regretting a treatment decision was higher when patients underwent RALP compared with open RP [16]. All of this information is worth giving to a patient to help him reach an objective decision.

A patient with a newly diagnosed prostate cancer who is counselled for his therapeutic options today should be informed that several equal surgical approaches are available and that despite all the perfectly styled Web pages, it is not the robot that makes the difference. He should be informed that there are indeed concerns about oncologic and functional outcomes and also evidence that in some significant papers the traditional surgical approaches look superior [16] and [17]. The patient who seeks counselling today is not that interested in potential future developments that can be expected in a certain surgical approach; he wants to know what to do now. And the answer today, in my opinion, is that if he decides to undergo surgery, he should seek an experienced centre, regardless of what surgical approach is used.

Conflicts of interest

The author has nothing to disclose.


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Martini-Clinic, Prostate Cancer Centre, University Hamburg-Eppendorf, Hamburg, Germany