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Erectile Function and Oncologic Outcomes Following Open Retropubic and Robot-assisted Radical Prostatectomy: Results from the LAParoscopic Prostatectomy Robot Open Trial: Beyond the Abstract

Since robot-assisted radical prostatectomy (RARP) was first developed, the technique has gained widespread popularity and is now the commonest modality of prostate cancer surgery across Western Europe and the United States. However, detractors point to its increased costs and zealous marketing, citing studies that show no benefit over the conventional open approach. A recent randomized controlled phase 3 trial from Australia showed no significant differences in positive surgical margins (a surrogate for cancer control), or recovery of urinary function sexual potency1. This led the authors to conclude that the surgical modality per se does not matter, it’s the surgeon that counts. But is this the whole truth?

While very experienced open surgeons like in the Australian study can get top-notch outcomes, the ‘average’ open surgeon gets far inferior results, as shown in the British Association of Urological Surgeons radical prostatectomy audit2. So yes of course patients should choose the best surgeon and it doesn’t matter whether he or she does the operation open or robotic, but in today’s age, there are far fewer open surgeons than robotic surgeons who can get these optimal outcomes. 

We tested this by comparing population-based outcomes from surgeons across Sweden. Unlike the Australian study, these were not highly selected high-volume surgeons, but a varied mix of the country’s surgeons who among them did half of all the country’s prostate cancer surgeries over the study period. 

There are a number of unique features in this Swedish study:

  1. All surgeons were experienced (but not so much so that the results could only apply to the handful of surgeons with such vast experience, as in the Australian study); to be included the surgeons had to have only done at least 100 operations.
  2. There were lots of surgeons included from lots of different centers (and thus the study becomes more generalizable than a tightly-regulated RCT).
  3. The questionnaires used to assess erectile-function recovery were highly detailed and far more comprehensive than the standard post-surgical assessments used by other investigators.
  4. The completion rate of questionnaires was impressively high: >90% across all domains and all questionnaires.
  5. Surgeons themselves reported what kind of nerve-sparing they had done at the time of surgery and these were then correlated with erectile-function recovery postoperatively, such that no reporter bias could have resulted.
Before detailing the study results, let’s start with a quick anatomic recap. 

The Figure below shows the prostate (P) with the rectum (Rec) behind, and the Denonvilliers fascia (DF) between the two. As the fascia goes around the prostate it splits into a layer that sticks on the prostate (prostatic fascia) as well as an outer covering, the lateral prostatic fascia (LPF). The nerves mostly lie between the prostatic and lateral prostatic fascial layers. Further lateral to the LPF lies another fascial layer, the pelvic fascia (PF) that covers the pelvic side wall muscle, the levator ani (LA). If the cancer is contained in the prostate, surgeons should try and dissect close to the prostate to spare the nerves lying medial to the LPF. This would aid erectile-function recovery without risking cancer control. However, if the cancer is outside the prostate (non-organ-confined), then surgeons should dissect widely towards the PF/LA such that they don’t leave cancer behind (a positive surgical margin).


In our Swedish study, we found that open surgeons had worse cancer control outcomes than robot surgeons for men whose disease was non-organ-confined. That means open surgeons were in general less able than robot surgeons to perform wide excision. Patients with prostate-confined cancer that were operated on by open surgeons also had worse erectile-function recovery than if they’d been operated on with robot-assistance, suggesting that open surgeons in general were also less able to dissect close to the prostate to fully spare the nerves. In other words, open surgeons tended to be in the same plane of dissection regardless of the extent of disease: they dissected too close to the prostate in non-organ-confined cases disease (when they should’ve gone wide), and too far away from the prostate in organ-confined disease (when they should’ve gone close).

While robot surgeons’ erectile-function recovery outcomes were well correlated with how close or far away from the prostate edge they said they were, this was not the case for open surgeons. Hence, although open surgeons ‘think’ they can dissect in different planes of dissection, the reality is they cannot. Given the improved vision and dexterity that robotic assistance affords the surgeon, these findings make complete sense, although have not been shown before.

Does that mean all open surgeons should convert to doing the operation with robotic assistance? No, of course not. What it means is that the robotic approach works best for the majority of surgeons and thus most trainee surgeons should learn to do the operation robotically. I suspect in a generation’s time over 99% of all radical prostatectomies will be done with robotic assistance and open radical prostatectomy will be confined to the history books rather like open cholecystectomy has been.

Written by: Prasanna Sooriakumaran

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References

  1. Yaxley JW, Coughlin GD, Chambers SK, et al. Robot-assisted laparoscopic prostatectomy versus open radical retropubic prostatectomy: early outcomes from a randomised controlled phase 3 study. Lancet. 2016 Sep 10;388(10049):1057-1066.
  2. www.baus.org.uk