The second most important surrogate for oncologic efficacy is lymph node status. The most common site of bladder cancer metastasis is the pelvic lymph nodes, and removal of these lymph nodes provides improved surgical staging and possibility of therapeutic benefit. Leissner et al. found significantly improved survival in 447 patients when more lymph nodes were removed [10] in open radical cystectomies. In that study a mean of 14 lymph nodes were removed. Patients with >15 nodes removed had better 5-year recurrence free survival (65 % vs. 51 %), less loco-regional metastasis (17 % vs. 27 %), and less distant metastasis (17 % vs. 10.5 %). This translates to an increased cancer-specific survival, regardless of stage and regardless of lymph node positivity. Although the limits of pelvic lymphadenectomy have been debated, it is suggested by some groups that an extended pelvic lymphadenectomy (above the iliac bifurcation) can improve staging and survival [11–13].

In addition to providing oncologic information, a lymph node dissection is a reflection of surgical skill and completeness of extirpation. It has been unequivocally demonstrated that an adequate lymph node dissection can be performed robotically. Table 14.2 lists five large studies involving 768 patients who underwent RARC with robotic lymphadenectomy. In this series, an average of 18 nodes per patients was harvested robotically. This easily meets the 10–14 lymph node standards set for ORC mentioned above by Herr et al. [12].

Multiple factors play a role in pathologic analysis including handling of specimens and quality of pathologic review [14], which vary from institution to institution; however, the comparative studies mentioned below (Nix et al. and Styn et al.) show similar lymph node counts between ORC and RARC in single center environments, obviating differences in pathologic review within a single institution.

Comparative trials are often regarded as superior to studies focusing only on one modality. So, how does RARC directly compare to ORC? Styn et al. performed a matched comparison of 68 patients undergoing RARC with 306 patients who underwent ORC at the University of Michigan [15]. They found no statistically significant differences in oncologic outcomes measures. PSM rates were 16 % vs. 11 % and mean lymph nodes removed were 14.3 and 15.2, in the RARC and ORC cohort, respectively. There were no mortalities in the RARC group at 30 and 90 days with a median follow-up of 8 months. More compelling, Nix et al. performed a prospective, randomized controlled trial comparing RARC with ORC in 42 patients at the University of North Carolina [16]. They had 0 PSMs in both groups and similar lymph node counts (19 in RARC group versus 18 in the ORC group). Furthermore, a prospective, randomized, controlled trial comparing RARC to ORC at the University of Texas Health Science Center San Antonio also shows no significant difference in PSM (5 % vs. 5 %) and lymph node yield (23 vs. 11) in 40 patients [17]. In concert, these studies demonstrate that the reported oncologic success of RARC hold up even in direct comparison to ORC. At present, there is a prospective, randomized, multi-institutional trial underway in the USA comparing ORC vs. RARC. In a few years, data from this trial will allow us to compare oncologic outcomes between the two approaches.

How does the quality of a robotic lymph node dissection compare to an open dissection? Davis et al. looked at 11 patients who underwent a robot-assisted radical cystectomy with pelvic lymph node dissection followed by a second look open pelvic lymph node dissection via minilaparatomy [18]. They found a robotic yield of 43 mean lymph nodes (range 19–63) while open second look yielded only a mean of four lymph nodes (range 0–8). In 80 % of these patients, no additional lymph nodes were found despite open dissection. This study suggests that robotic lymph node dissection can be performed with a completeness approaching that of open surgery.

As with any new procedure, especially one that involves a relatively new technology such as the da Vinci robotic system, there is a period of time during which the inexperience of the surgeon makes the operation more difficult. This is commonly referred to as the learning curve. Some surgeons would say that they passed the learning curve once they felt comfortable performing a procedure. Given the subjective nature of what “comfortable” means to various surgeons, there are attempts to look at more objective metrics to measure the learning curve of an operation and to establish its effect, if any, on oncologic efficacy.

Given the infancy of RARC, the long-term oncologic outcomes of ORC vs. RARC have yet to be firmly established. Moreover, determining long-term oncologic outcomes in early vs. late learning curve cases also remains to be established. In the meantime, however, there has been literature published regarding operative and postoperative complications, oncologic outcomes, and survival. Pruthi et al. retrospectively reviewed their first 50 patients undergoing RARC, dividing them into quintiles, and analyzing metrics such as estimated blood loss (EBL), total OR time, margin status, number of lymph nodes removed, and complication rate [19]. They noted differences in EBL and operative time, but positive margin rate and lymph node yield were not significantly different over the course of the learning curve, when evaluated by quintile and by halves.