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Current Status of Robot-Assisted Radical Prostatectomy: Progress Is Inevitable

Current Status of Robot-Assisted Radical Prostatectomy: Progress Is Inevitable

Introduction

Prostate cancer is the most common non-skin cancer among men in the United States.[1] In 2012, it is estimated that 241,740 men will be diagnosed with prostate cancer and that 28,170 will die of the disease.[1] Over the years, due to increased awareness and widespread adoption of prostate-specific antigen testing, the disease demographics have shifted towards organ-confined disease and a younger patient population.[2]

Vipul R. Patel

Radical prostatectomy (RP) is one of many treatment options available to men with clinically localized prostate cancer, and it may be the preferred option for some, based on their cancer risk, age, comorbidities, and preferences.[3] The procedure is associated with excellent cancer control rates.[4] Overall prostate cancer–specific survival (CSS) at 15 years after prostatectomy has been shown to be approximately 93% to 95%.[4] Despite its current preferred status, previously RP was not the first-line approach, due to the associated high levels of incontinence and erectile dysfunction. However, after the anatomical approach to RP was introduced in the 1980s by Walsh et al,[5] with consequent improved functional outcomes, RP came to be considered one of the first-line treatments for localized prostate cancer.

Evolution of RP

Traditionally RP was performed by the open method (ORP). As minimally invasive surgery (MIS) was adopted and popularized in other surgical fields, especially in general surgery (eg, minimally invasive cholecystectomy), urologists began to experiment with MIS. The first laparoscopic RP (LRP) was done in 1991, by Schuessler et al.[6] French surgeons were responsible for popularizing LRP, and it slowly gained acceptance.[7] However, due to the inherent technical demands of the procedure, it was not widely accepted. LRP had a long learning curve[8] and was difficult for laparoscopically naive surgeons to grasp.

The next major advance was the development of the robotic interface and robot-assisted laparascopic radical prostatectomy (RALP). The first RALP was performed in 2001, by Binder and Krammer.[9] With advantages that included three-dimensional visualization, miniaturized wristed instruments, seven degrees of freedom, magnification, and improved ergonomics, RALP was widely adopted—such that by 2010 almost 80% of all prostatectomies in the US were done with robot assistance.[10]

Although the technique has been widely adopted, questions have been raised regarding the efficacy of RALP. Doubts arise primarily due to of the lack of randomized comparative trials involving the various approaches to RP. The probability of there being well-structured randomized trials to answer skeptics’ questions seems lower by the year, and we may have to reconcile ourselves to the fact that such trials may never happen—chiefly because of patient choice. In situations like this, in which experimental data are not available, observational data must be utilized.

With this background in mind, let us look at the current status of the debate between RALP and ORP—and at future perspectives for the surgical approach in prostate cancer.

Perioperative Outcomes

The main reasons for the introduction of MIS were smaller incisions, shorter hospital stays, and decreased convalescence with lesser complications. Not surprisingly, most studies analyzing perioperative outcomes favor RALP over ORP.[11,12] In a recent landmark paper that provides a contemporary snapshot of current perioperative outcomes, Trinh et al[13] assessed the rate of RALP utilization and the differences in perioperative complication rates between RALP and ORP. Of 19,462 surgeries performed, 61.1% were RALPs, 38.0% were ORPs, and 0.9% were LRPs. In multivariable analyses of propensity score–matched populations, patients undergoing RALP were less likely to receive a blood transfusion (odds ratio [OR]: 0.34; 95% confidence interval [CI], 0.28–0.40), to experience an intraoperative complication (OR: 0.47; 95% CI, 0.31–0.71), to experience a postoperative complication (OR: 0.86; 95% CI, 0.77–0.96), or to have a prolonged length of stay (OR: 0.28; 95% CI, 0.26–0.30). Moreover, when individual postoperative complications were examined, cardiac, respiratory, and vascular complications were found to be less likely to occur in patients undergoing RALP than in patients undergoing ORP, indicating a beneficial effect of RALP on medical complications as well. Previous population-based studies showed shorter lengths of stay and fewer respiratory complications, miscellaneous surgical complications, and strictures.[14,15] In our own published series of 2500 RALPs, we encountered a total complication rate of 5.08%. Out of all 2500 cases, the majority (4.04%) were Clavien grade 1 or 2.[16]

Oncologic Outcomes

Cancer cure is the primary goal of prostatectomy. The importance of oncologic outcomes such as positive surgical margins (PSMs) and biochemical recurrence (BCR) rate cannot be overemphasized. PSM rate may be considered as a surrogate for short-term oncologic outcomes, although it may not always correlate with BCR. Moreover, PSM rate also indicates the quality of surgery. However, long-term outcome measures such as BCR rate and cancer-specific survival are gold standards with regard to oncologic outcomes.

In a systematic review and cumulative analysis of published literature up to 2009, Ficarra et al[17] analyzed PSMs in ORP and RALP series. In their analysis, a statistically significant difference in favor of RALP was identified (relative risk [RR]: 1.58; 95% CI, 1.29–1.94; P < .00001). Similarly, sensitivity analysis of prospective studies reconfirmed a statistically significant advantage for RALP over ORP (RR: 1.90; 95% CI, 1.24–2.89; P = .003).

Tewari et al[18] conducted a systematic review and meta-analysis comparing retropubic, laparoscopic, and robotic prostatectomy abstracted data from 400 original research articles representing 167,184 ORP patients, 57,303 LRP patients, and 62,389 RALP patients (total: 286,876). Primary outcomes were PSMs and complication rates. The overall PSM rates were 24.2% for ORP patients and 16.2% for RALP patients; pT2 PSM rates were 16.6% for ORP patients and 10.7% for RALP patients, but the difference did not attain significance after propensity score adjustment and Hochberg correction (overall PSM, P = .002; pT2 PSM, P = .01). The rates for pT3 cancers (42.6% ORP, 39.7% LRP, and 37.2% RALP) were not significantly different after propensity adjustment and Hochberg correction. At the very least, these results indicate that RALP is equal to if not better than ORP in terms of PSMs.

With regard to oncologic outcomes, Masterson et al,[19] in a retrospective review of 1041 patients who underwent ORP or RALP between 1999 and 2010, utilized a single surgeon and a pathologist to perform pathologic evaluation, using whole-mount sectioning techniques and tumor mapping. A total of 357 ORP patients and 669 RALP patients were evaluated with regard to PSMs and oncological outcomes. Comparing biochemical recurrence-free survival rates according to surgical approach, no differences were seen at 24 or 60 months postoperatively between ORP patients (87% and 71%, respectively) and RALP patients (87% and 73%, respectively). Similarly, Magheli et al[20] matched 522 patients undergoing RALP with ORP patients; short-term follow-up yielded BCR rates of 93% for ORP and 94% for RALP. However, longer-term results are required for effective comparison of oncologic outcomes. Current results indicate that oncologic outcomes are at least similar if not better in RALP patients than in the open cohort.

Functional Outcomes

With long-term survival ensured for localized prostate cancer, functional outcomes have become the focus of prostatectomy. Analyzing functional outcome data is hampered by the lack of standardized criteria. A large systematic review by Berryhill et al[11] found RALP continence rates to range from 73% to 91% and ORP rates from 54% to 87%. Koehler et al,[21] in a multicentric, longitudinal study of 350 prostate cancer patients (166 RALP and 184 ORP) in 7 German hospitals, assessed early continence rates and found no significant difference between the approaches at 3 months (44% RALP and 40% ORP). Hu et al[14] found a significantly higher rate of urinary incontinence diagnoses for minimally invasive RP compared with ORP (15.9 vs 12.2 per 100 person-years, P = .02). Nevertheless, with regard to analysis of the need for urinary incontinence procedures, which is a more realistic urinary-continence end point, the two population-based studies (Hu et al[14] and Lowrance et al[15]) found no significant difference in the need for post-RP urinary-continence procedures. Coelho et al,[22] on analyzing data from high-volume centers, found that weighted mean continence rates were 80% for ORP and 92% for RALP.

The potency outcomes also do not have standardized assessment protocols. In addition, the type of nerve-sparing procedure was not indicated for pertinent data and so could not be used as the basis of comparison. The rudimentary theory used in most ORP series is that patients with bilateral nerve-sparing procedures should have better functional outcomes than those with only unilateral nerve-sparing or nerve-excising procedures. In the robotic era, however, nerve preservation has been superseded by incremental/partial nerve preservation,[22] with better potency outcomes seen in men who undergo partial excision than in those who undergo full bilateral or unilateral excision. Furthermore, with the experience, improved vision, and magnification associated with the advent of robotics, several visual cues have been identified that can be used to grade the nerve sparing in a standardized, reproducible manner.[23,24] In a nonrandomized prospective trial comparing ORP and RALP, Tewari et al[23,24] found that the median time to erectile function recovery was 440 days after ORP and 180 days after RALP. Similarly, the median time to intercourse was 700 days after ORP and 340 days after RALP.

Ficarra and associates defined potency as an International Index of Erectile Function (IIEF)-5 score of >17. Limiting their analysis to only patients who underwent bilateral nerve-sparing RP with at least 1 year of follow-up, they found that 49% of ORP patients and 81% of RALP patients were potent by their definition (P < .001). Their analysis did adjust for the effects of age, preoperative erectile function, and comorbidity, all of which may have been very different between the two groups.[17] These results reflect the outcomes from our unit, where we have seen continence rates of 97.4% and potency rates of 91.5% in preoperatively potent men who undergo bilateral nerve sparing. Thus, in terms of functional outcomes, RALP seems again to have an advantage over ORP.

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