Comparison of Robotic-assisted versus Retropubic Radical Prostatectomy Performed by a Single Surgeon

Discussion

This is the first report of a comparison of RALP versus RRP performed by a single surgeon in Taiwan. The goal was to elucidate the results of the initial experience during the learning curve for RALP. Does a surgeon's immature technique with RALP compromise the interests of the patient? Data showed that RALP is promising because of its reasonable operation time and moderate complication rates. Short-term outcomes of robotic-assisted radical prostatectomy were shown to be better than those of RRP in this series. A single surgeon performed the surgeries in this study to eliminate the variability in learning curves for RALP and RRP among different surgeons. Menon and Tewari's group reported a comparison between outcomes of several different surgeons performing open procedures with the outcomes of one robotic surgeon (7, 16). Two procedures were performed by different surgeons with bias related to variability of training, technique and experience. These results are consistent with those of Menon's study, which compared 30 initial patients undergoing RALP and 30 consecutive patients undergoing RRP, concluding that surgeons experienced in conventional RRP can learn RALP within a reasonable time and with acceptable complication rates (7). Baseline, operative and post-operative parameters between Menon's series and Ou's series undergoing RALP are shown in Table V. The presented series had higher PSA scores and clinical stages than Menon's series. The operative parameters were similar in both groups. At this institution, the learning curve for RALP for a single surgeon included console time and anastomosis time. The average console time was reduced from 295 minutes to 214.5 minutes to only 166.5 minutes in the first 10 cases, second 10 cases and third 10 cases, respectively. The anastomosis time was reduced from 59 minutes to 44.5 minutes to 39.5 minutes in the first 10 cases, second 10 cases and third 10 cases, respectively. The surgeon's skill became stable with a console time of less than three hours and vesicourethral anastomosis time of 40 minutes, with a learning curve of about 30 cases. Ahlering et al. reported an anastomosis time of 50 minutes for cases 1 to 5 and 21 minutes for cases 36 to 45 (9). More experience is needed for delicate bladder neck dissection and skillful sutures in order to achieve an anastomosis time of less than 30 minutes. Console time was among the parameters that improved significantly between the initial and later surgeries. The console time in this case was 226 minutes. This time is reasonable compared to that of 233 minutes reported by Menon for the initial 30 cases (7).

After completing the learning curve for RALP, outcomes of RALP procedures were much improved. A comparison of results of the first 200 RALP surgeries performed by Menon with 100 consecutive contemporary RRP surgeries confirmed the advantages of RALP with regard to blood loss, transfusion rates, postoperative pain and hospitalization time (16). Ahlering et al. reported analyzing their clinical experience with cases 1 to 45 (9), and they believed that the RALP learning curve was sufficiently mature. Ahlering and colleagues compared the last 60 RALP procedures (cases 46 to 105) with 60 RRP procedures and concluded that RALP had oncologic and urinary outcomes that were at least equal to RRP outcomes. RALP offers the benefits of minimally invasive surgery and does not compromise clinical or pathologic outcomes (17).

The tamponade effect prevents venous bleeding under pneumoperitoneum of 12-15 mmHg during RALP procedures. Mean estimated blood loss (EBL) was 329 mL for RALP and 970 mL for RRP in Menon's series (7). The transfusion rate was 7% for RALP and 30% for RRP. In this study, the mean estimated blood loss (EBL) was 314 mL for RALP and 912 mL for RRP. The high transfusion rate of 60% with RRP in this series is attributed to “transfusion trigger” by anesthesiologist's decision in the clinical practice during surgery. In this study of RALP outcomes, blood loss and transfusion rates declined from 353 mL and 20% in the first 15 cases to 276 mL and 6.7% in the subsequent 15 cases. These results are consistent with Menon's findings of initial 20 cases and subsequent 10 cases in which blood loss decreased from 400 mL to 202 mL and the blood transfusion rated decreased from 6% to 0% (7).

The greatest advantage of RALP is rapid recuperation and a very short hospital stay. Patel reviewed the length of hospital stays for RALP and reported only 1.08 to 5.5 days (13). Taiwanese patients are reluctant to be discharged from the hospital if they are still catheterized. Furthermore, in Taiwan, ward expenses are paid by health insurance, not by patients. Therefore, postoperative hospitalization may be longer in certain cultures and under different health insurance coverage systems. The postoperative stay was shorter following RALP surgeries than following RRP in our series. Menon et al. reported that RAP patients were discharged earlier from the hospital than RRP patients (7). Ahlering et al. reported the same trend of hospital stays with an average of 25.9 hours for RALP and 52.8 hours for RRP (17).

In Menon's series, duration of catheterization was 13.7 days in the RRP group versus 10.7 days in the RALP group, compared to 9 days in the RRP group versus 7 days in the RALP group in Ahlering's series and 8.37 days in RRP group versus 7.33 days in the RALP group in this series. The important thing is continence rate and the time to achieve continence. One benefit of RALP is better continence rates and an earlier return of continence because of improved preservation of the urethral sphincter and urethral length. A high-quality, 3D endoscopic camera in the da Vinci system provides better visualization of the apex, allowing the surgeon to finely dissect and preserve the urethral sphincter (18). Pasticier et al. reported that 80% of patients achieved restored continence at 9 days (19). Patel et al. reported continence rates of 47%, 82%, 89%, 92% and 98% at 1, 3, 6, 9 and 12 months, respectively (11-13). Ahlering et al. reported no difference between groups in the continence rate at three months (76% for RALP, 75% for RRP) (17). In this series, the continence rate at 12 months was similar in both groups, although statistically significant differences were shown in the three-month continence rate between the RALP group (76.6%) and the RRP group (36.7%). The probable reason for the relatively good continence results in the RALP group is that the puboprostatic ligament-sparing technique in this modified procedure improves the speed of return of urinary continence. Previous studies have reported that the median time until continence was achieved after surgery was significantly shorter (p=0.01) for the puboprostatic ligament-sparing group than for the standard method (6.5 and 12 weeks, respectively) (20). Takenaka et al. recently reported that preservation of the puboprostatic collar and puboperineoplasty contributed to early recovery of urinary continence after robotic radical prostatectomy, with an immediate continence rate of 42.1% just after catheter removal (21).

In this study, 53.3% (16 of 30) RALP patients had an opportunity to receive bilateral or unilateral neurovascular bundle preservation, and the overall postoperative potency and intercourse rate at 12 months was 87.5% and 60%, respectively. Patients receiving RRP had only a 6.2% overall potency and intercourse rate (2 of 30 patients) with NVB preservation. The greater incidence of potency and intercourse rates with RALP are due to improvements in technique andpatient's demand. The factors that influence erectile function include previous level of sexual function, age and intraoperative injury of the neurovascular bundle. Menon et al. reported potency and intercourse rates of 82% and 64%, respectively, in patients younger than 60 years of age, and 75% and 38%, respectively, in patients older than 60 (16). Recently, the new technique of prostatic fascia preservation and athermal robotic techniques to avoid neurovascular injury have resulted in better potency rates of 97% at one year postoperative follow-up (22, 23).

With respect to oncological outcomes, little difference was seen in positive surgical margin (PSM) rate in T2 (13.3% for RALP vs. 0% for RRP). The incidence of PSM in pathologic T3 was higher in RALP than in RRP (86.7% vs. 40%, respectively). A PSA failure rate of 20% at 15 months for RALP and 16.7% for RRP were also observed. The high incidence of PSM in RALP is caused by more advanced tumors, inadequate surgical technique and poor patient selection for NVB preservation. In Patel's review, the PSM rate range was 0 to 20% for patients at T2 and 0 to 75% for T3 (13). Ahlering et al. reported one surgeon's outcomes from 60 RALP procedures in which the PSM rate for pathologic stage >T3 was 50% (17), while Atug et al. reported that the PSM tended to diminish from 45.4% to 21.2% to 11.7% as the surgeon's experience increased over about 30 cases (24). Reducing the positive surgical margin rate is undoubtedly a challenge for the novice as experience is gained during the initial 30 cases. The rate of positive surgical margins and nodes in advanced tumors was higher in this series than in Menon's series (7). This series had higher PSADs (due to higher PSAs and lower prostate volumes) than in Menon's series (0.47 vs. 0.169, respectively). Radwan et al. reported that PSAD results are strong predictors of advanced pathologic features and biochemical failure after radical prostatectomy (25).

Smith et al. reviewed papers related to RALP and RRP and concluded that RALP is consistently associated with decreased blood loss, limited postoperative pain and shorter hospital stays. Most intra-institutional comparisons demonstrate better postoperative continence and potency with RALP. RALP provides outcomes at least comparable, and in some measures, superior to open surgery (26). However, surgeons with extensive experience with RRP may set higher standards for the learning curve because of expectations. Webster et al. reported a nonrandomized study comparing 159 RALPs and 154 RRPs. The authors did not show any significant advantage in terms of postoperative pain scores between RALP and RRP groups (27). They also reported similar transfusion rates in open and robotic groups (28). Smith reported that the learning curve for RALP was 150 procedures, comparable to routine RRP (29). Surgeon comfort and confidence comparable to that of RRP did not occur until 250 RALP procedures had been performed (29).

In conclusion, performance of RALP is continuing to grow because of patient interest, benefits and demand. RALP is a minimally invasion procedure with less blood loss and lower transfusion rates than RRP. It offers a greater chance of preserving NVB and more rapid convalescence than RRP.