Robotic vs. open RP: Better EF recovery seen with robot

“Journal Article of the Month” is a new Urology Times section in which Badar M. Mian, MD (left), offers perspective on noteworthy research in the peer-reviewed literature.  Dr. Mian is associate professor of surgery in the division of urology at Albany Medical College, Albany, NY.

Robot-assisted radical prostatectomy (RALP) was associated with earlier and increased rate of recovery of erectile function when compared to radical retropubic prostatectomy (RRP) and a slightly higher but acceptable rate of positive surgical margins (PSM), according to a study published online in European Urology (Sept. 4, 2017).

This Swedish study (LAParoscopic Prostatectomy Robot Open, or LAPPRO) was based on prospectively collected data on 2,545 men who underwent either RRP (753 men) or RALP (1,792 men). Between 2008 and 2011, 50 different surgeons from 14 centers performed the procedure according to the technique utilized at that center (seven RALP and seven RRP), without switching to the other technique. While this is not a randomized controlled trial, the surgical approach was based on the patients’ region of residence and the service available at their “assigned” hospital, thus introducing a degree of chance to the assignment of the surgical approach.

Overall, 31%, 61%, and 8% were in the D’Amico low-risk, intermediate-risk, and high-risk group, respectively. Nearly two-thirds of the men reported normal erectile function pre-op, defined as erections sufficient for intercourse on more than half of occasions. At 3, 12, and 24 months, data about the extent of erectile function recovery were collected by a third party.

The patient-reported recovery was classified into five sub-categories, ranging from none or occasional or partial to full erections. Men with sufficient erections on less than half of occasions were considered to have recovered potency. Surgeon-reported extent of nerve-sparing technique was recorded, such as unilateral or bilateral, and interfascial or intrafascial on each side, providing seven sub-categories.

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More men underwent some attempt at nerve-sparing approach during RALP, regardless of the risk category. Recovery of erections was significantly higher with RALP for the entire cohort and for the low/intermediate-risk group, but no statistically significant difference was noted in the high-risk group. Also, the surgeon-reported nerve-sparing technique was very highly likely to correlate with the eventual recovery of erections after RALP, but not after open surgery.

When comparing the PSM rate between RALP and RRP, the PSM for pT2 disease was 7% higher in the RALP group (17% vs. 10%). Conversely, the PSM rate for pT3 disease was 14% higher in the RRP group (48% vs. 34%).

Interestingly, while the PSM rate for pT2 disease was higher in the RALP group, the PSA recurrence rate (defined as PSA >0.2 ng/mL in 2 years) was similar for RALP and RRP. The PSA recurrence rate in pT3 disease was significantly higher in the RRP group (21.5% vs. 13.5%). Speculations about the higher PSM with RALP in low-risk, early-stage disease have been discussed by others and are also applicable here. It’s very likely that the improved visualization during RALP facilitates dissection in the tissue planes close to the prostate capsule; thus, capsular disruption.

The lack of difference in the recurrence rate may be due to the increased likelihood that the PSM in pT2 disease is iatrogenic due to purposeful dissection close to the prostate capsule or an artifact of improper tissue handling and not due to the aggressiveness of the cancer. In pT3 disease, the PSM is more likely a reflection of the aggressive biologic behavior of the cancer, resulting in higher recurrence rate.

Next: Extent, location of PSM not included

Extent, location of PSM not included

Because the study is not a randomized controlled trial, it has the expected weaknesses of an observational study, many of which are partially mitigated due to the circumstantial assignment of the surgical approach. The extent and location of PSM is an important variable that is missing from the report. Unlike a single-center study, the large number of surgeons attempting to consistently replicate a certain dissection technique seems quite improbable.

However, the inherent variability among surgeons may also make this data more applicable to the general population. The somewhat “captured” nature of the cohort in the Swedish national health care system resulted in a very high follow-up response rate of over 90%. Further, the collection of data by a third-party and patient-reported erectile function provides additional validity to the data.

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The apparently mixed report on outcomes between RALP and RRP may at first seem to offset each other, but it’s important to look at the functional outcomes and oncologic control in the proper context. The PSM is only a surrogate of oncologic control and in pT2 disease appears to be less clinically relevant than the ability to preserve or recover erectile function. There is clearly a negative clinical impact of PSM in pT3 disease in terms of recurrence and need for additional treatment. RALP seems to provide better cancer control in these men, with somewhat comparable recovery of potency.

A thoughtful discussion of the tradeoffs and the importance of oncologic and functional aspects of the outcomes is required on an individual basis.

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