As robotic surgery becomes a more accepted treatment modality for clinically localized prostate cancer, many urologists are struggling to incorporate this technique into their therapeutic armamentarium. Increasingly, surgeons are foregoing open retropubic approaches with a technically challenging robotic-assisted technique for which efficacy data are currently limited but growing. It is the intent of our analysis to objectively analyze the robotic approach from an oncologic standpoint, and in doing so, to characterize the oncologic and therapeutic efficacy of this relatively new and growing technology.
Although the ultimate measure of any intervention is the ability to prolong long-term survival, modifications in surgical technique can be assessed in the short-term by analyzing pertinent oncological principles. One such variable is pathology margin status. It is generally agreed that a positive margin is indicative of incomplete tumor resection and bears significant prognostic importance. Several institutions have demonstrated the independent prognostic significance of positive surgical margins across all stages of disease.13–15
Han et al16
further point out that the rate of positive surgical margins has declined dramatically from around 40% during the early 1980s to less than 10% more recently. Although these observations are likely multifactorial, the lower positive margin rates over the past decade are largely attributable to the stage migration that has occurred in the era of PSA screening. It is imperative, however, to also consider contemporary refinements in preoperative planning, biopsy strategies, and surgical technique.17
As we embark on the robotic age for the treatment of prostate cancer, it is essential that we adhere to surgical principles learned over the last 3 decades.
In this study, we report an overall positive margin rate of 17%. During the first half of our experience, we noted a 23% positive margin rate, which declined to 11% over our last 70 consecutive patients. Further, no difference existed in the pathologic distribution of tumors between our initial 70 patients and our latter 70 (9 vs 10 cases of ECE). Collectively, these data suggest that the decline in the positive margin rate is most attributable to an improved surgical skill set in the robotic technique rather than a decrease in the number of biologically aggressive tumors. Subset analysis of the data also notes a significantly lower incidence of positive margins when comparing specimens with organ-confined disease with those with extracapsular extension (12% vs. 47%, P<0.001). Noteworthy, however, is the decrease in positive margin rates from 56% to 25% in the pT3 subgroup of tumors during the evolution of our experience. This underscores that robotic prostatectomy is a reasonable surgical alternative for organ-confined, as well as pT3 disease. Thus, even in our initial robotic experience, the results compare favorably with those of other reported robotic series, as well as with the current oncologic gold standard open retropubic approach.18,19
The specific location of positive margins is explainable both by surgical experience and technique. As depicted in
, bladder neck positive margins declined over 3-fold when comparing the first half of our robotic experience and our most recent surgical series. The antegrade approach utilized during a robotic prostatectomy can be quite challenging and choosing the appropriate location for incision of the bladder neck can be difficult. As our experience in robotic surgery has matured, we have learned to take a wider bladder neck and robotically reconstruct the bladder as necessary. This modification has probably resulted in decreased positive bladder neck margins as our experience increased. In terms of the anterior and apical margins, we noted that 15% (5/33) of all positive margin sites were at each of these 2 anatomic locations, respectively. This compares favorably with other published reports in which the apical positive margin rates range from 5% to 28%.20
We believe that the anterior and apical dissection is enhanced with the robotic approach likely due to the use of an angled lens resulting in improved visualization of the dorsal vein/urethral complex.
At 1-year follow-up, 97% (139/143) of men were fully continent without the requirement of any pads. This compares favorably with continence data published following the open retropubic approach. Our 3-month follow-up data, however, indicate that less than 50% of patients are fully continent at this time point. Anecdotally, this is lower than the continence rates we have observed for our contemporary open retropubic prostatectomy series. One possible explanation is that the enhanced robotic visualization may result in excessive dissection of the striated sphincter complex beyond the apex of the prostate. To improve the early continence rates, we have made several modifications in our current technique including tacking the urethra to the periosteum of the pubis and avoiding excessive dissection beyond the apex of the prostate. With such modifications, our short-term continence rates have improved in a more contemporary group of patients (data not shown).