ICUD is theoretically less invasive than ECUD, including reduced fluid loss from the intestines, reduced bleeding to prolong the pneumoperitoneum time, and shorter skin incisions and ureteral detachment areas.[6] However, when adapting ICUD, prolongation of the operation time, and damage to the ureter and intestinal tract by robotic arms are of concern. The number of studies evaluating the benefits of ICUD compared with ECUD is increasing, but no consensus has been reached.[3, 9, 10, 11]
In our analysis, although complication rates within 90 days were not significantly different, the RARC + ICUD group had slightly better outcomes. The most common complications were infections in both groups. In the RARC + ICUD group, high-grade complications (Clavien-Dindo grade 3–5) were noted in the early stage of ICUD introduction. In a review of 26 institutions, although RARC + ICUD was associated with higher-grade complications than RARC + ECUD, they decreased with time.[6] Similarly, at our institution, there were few complications in the late stage of ICUD introduction and no serious complications developed in the latter stages in the RARC + ICUD group.
In our study, we divided the operation time into time to cystectomy, time of lymph node dissection, and time of urinary diversion for procedure comparison because it is difficult to directly compare RARC + ICUD and LRC + ECUD. As a result, the time to cystectomy (median 163 vs. 194 min) and time of urinary diversion with the ileal conduit (median 161 vs. 201.5 min) were significantly shorter in the RARC + ICUD group. The total operation time (median 516 vs. 532.5 min) and the time of lymph node dissection (median 84.5 vs. 92 min) were equivalent between the groups.
There have been many comparisons between ICUD and ECUD. In the 83 previous studies, the mean operative time for the ileal conduit and neobladder by RARC + ICUD was 307 and 428 min, respectively, compared with 428 and 426 min by RARC + ECUD.[13] Furthermore, in a report on 10 institutions, the operative time for LRC + ICUD with an ileal conduit was approximately one hour longer (median 676 min vs. 616 min, p = 0.002) than that for LRC + ECUD with an ileal conduit.[14] Thus, there were many reports on the operation time. In our study, there were no differences in the total operation time between the groups. However, by distinguishing the operation time for each part, we revealed that the operation time for cystectomy and urinary diversion with an ileal conduit by ICUD is shorter than that by ECUD.
In the initial stage of ICUD, there was a long operation time until the procedure was standardized, but once learned, ICUD with an ileal conduit was more stable than ECUD and shortened the operation time. In our experience, for ECUD with minimal incisions, especially in obese patients, it was difficult to pull the ureter out of the body and to anastomose due to the long distance between the suture position and the final position of the urinary tract. As a result, we needed longer incisions, which prolonged the operation time. On the other hand, ICUD enabled us to anastomose at the final position of the urinary tract and the skin incision was shorter, which made the operation more comfortable than ECUD with minimal incisions. As such, ICUD was performed in a shorter time than ECUD.
The difference in time to cystectomy reflected the difference in procedure between the robot and laparoscopy. RARC was previously associated with a lack of tactile feedback and longer operative time than LRC.[11] However, in a recent report, RARC had a similar operation time (median 326 vs. 315 min, p = 0.279) to LRC.[12] The operational stability and robotic ergonomics of RARC may reduce the time to cystectomy.
Focusing on other secondary outcomes, length of hospital stay, number of days to walking, drinking and oral intake, and postoperative C-reactive protein in the RARC + ICUD group were significantly lower than those in the LRC + ECUD group. This suggested that the recovery time of the RARC + ICUD patients was superior to that of the LRC + ECUD patients. Thus, RARC + ICUD was less invasive than LRC + ECUD.
The number of eLND was significantly greater in the RARC + ICUD group than in the LRC + ECUD group. Zhang reported more eLND (17.8 ± 5.7) in the RARC group than standard LND (12.6 ± 6.2).[15] In this study, when performing eLND during RARC, we were able to extract more lymph nodes than when performing eLND during LRC. Therefore, RARC may enable more cranial lymph node dissections, especially common iliac and anterior sacral lymph nodes, than LRC.
This study had two limitations. First, the number of patients was small. Although we had a small sample size, we demonstrated an advantage to introducing ICUD even in a facility where there were only approximately 20 cases of total cystectomy annually. Second, the follow-up period was relatively short. As the follow-up period was significantly shorter in the RARC + ICUD group, the long-term oncological outcomes between groups were unable to be compared.