RALP was first described in 2001 [8
] and has become the most common surgical approach for performing RP in the USA [1
]. Despite this rapid adoption, there are only limited data comparing oncological outcomes of open vs robotic RP in contemporaneous cohorts. In this study we compared the outcomes of four experienced surgeons, two performing ORP and two performing RALP, over a concurrent time period at a single centre and demonstrated no significant differences with respect to positive margin rates or BCRFS even in a patient population that is enriched for high risk disease [9
]. Ideally, a comparison of oncological outcomes in patients undergoing RP using two different surgical approaches would be made through a randomized trial. While no such trial exists, several investigators have used single institutional databases to establish the equivalence of these approaches [10
]. Our results are consistent with these previous investigations; however, there are several unique considerations that make our findings of additional value. First, we utilized several measures to reduce potential biases that may have impacted previous investigations. Second, the higher risk nature of our cohort compared with other studies demonstrates that these surgical approaches can result in similar outcomes even in this population.
In the present study, in order to reduce any impact of the learning curve, which has previously been established to affect oncological outcomes, we only included data from contemporary experience of urological oncologists who had performed well in excess of 250 RPs using their predominant technique [13
]. Regardless of surgical approach, for all operations the primary focus was to adhere to strict oncological principles. Seminal vesicles were completely excised in all cases. A full PLND was performed for all patients with ≥2% risk of nodal invasion based on previously validated nomograms and selected patients whose risk fell below this number. This resulted in a large and similar median nodal yield in each group [15
]. This contrasts with studies that demonstrate that RALP surgeons are up to five times more likely to omit PLND than ORP surgeons, even for high risk cancers [17
For the current cohort, all pathological tissue was collected, processed and analysed by the same group of dedicated genitourinary pathologists in identical fashion. Surgical approach was determined by surgeon and patient, and there was no specific selection bias based on disease risk. In contrast to many large robotic series, low risk patients at MSKCC are routinely encouraged to consider active surveillance. This results in a generally high risk surgical cohort with similar demographics and oncological characteristics between the ORP and RALP groups [9
Additionally, to control for any remaining differences in case mix, we performed a multivariable regression model using a validated nomogram to adjust for any differences in Gleason score, volume of disease, PSA or clinical stage between the two cohorts. We then repeated this analysis using NCCN risk groups to demonstrate the outcomes across risk groups. In both of these analyses we found that surgical approach had no impact on the risk of BCR. Despite suggestions that ORP may provide better cancer control for men with high risk cancers [19
], we found no evidence to support this belief (). Within the limits of the power of our study to detect any significant difference and with relatively short follow-up, we found that RALP, when performed by highly experienced surgeons, was not associated with lower rates of BCRFS or higher rates of positive surgical margins.
Not surprisingly the proportion of patients with positive surgical margins was greater for both ORP and RALP as pathological stage or NCCN risk group increased. While there were differences between surgical approaches by NCCN risk group, they were largely ameliorated when patients were stratified by pathological T stage, and reflective of the limitations of risk groupings [20
]. The ability to achieve negative surgical margins depends on both the disease and the plane of dissection. Surgeons must achieve a balance between preservation of the neurovascular bundles and wider resections of tumours in cases suspected of having extracapsular extension. In only 2% of the cases were both neurovascular bundles completely excised; complete or partial bilateral nerve sparing was performed in 91% of the cohort.
Even with evidence suggesting that RP may be more effective than other treatments at controlling high risk disease [21
], there is growing concern that surgery is under-utilized in this population [22
]. As fewer ORPs are being performed in the USA [1
] and fewer trainees are gaining familiarity with the open approach, it is particularly important to demonstrate that for higher risk patients equivalent outcomes can be achieved using robotic assistance. Our findings demonstrate no worse outcomes for higher risk patients receiving RALP when emphasis is placed on strict adherence to oncological surgical principles.
It would be difficult to demonstrate superiority in cancer control of one surgical approach compared with another, since such differences, if they exist, are likely to be dwarfed by large heterogeneity among even experienced surgeons [23
]. Within this small group of highly experienced surgeons, we observed larger differences between surgeons than between approaches. This suggests that surgical approach should be based primarily on the skill and confidence of the surgeon to perform the appropriate and complete operation rather than on the technique.
Our findings are consistent with prior investigations comparing outcomes of ORP and RALP that have not found that surgical approach had an impact on BCRFS. Barocas et al
] compared 491 patients who underwent ORP to 1413 patients who underwent RALP performed by several surgeons at a single institution over a concurrent time frame. The case mix was such that the ORP cohort had higher PSA values, Gleason scores and positive margin rates and more palpable disease. Despite these disparities they found no significant difference in BCRFS. Krambeck et al
] compared 294 RALP patients with 588 matched ORP patients and noted that 3-year BCRFS rates and margin positivity rates were not significantly different between groups. The study may have been influenced by the heterogeneity of the surgeons, as the majority of the RALPs were performed by one surgeon whereas 17 different surgeons performed ORPs. Di Pierro et al
] performed a prospective study comparing oncological outcomes of two consecutive series of patients treated by ORP or RALP. They found no significant difference in BCRFS between groups but the study was limited by its consecutive cohort design and because all RALPs were performed by one surgeon with only 6 months of experience.
Our study has limitations, particularly the relatively short follow-up. RALP is a relatively new procedure, not commonly performed at MSKCC until 2007. With longer follow-up, our results with regard to BCR may be different. Furthermore, we did not distinguish between patterns of PSA recurrence, such as those associated with early appearance of metastases or the more indolent slowly rising PSA levels often associated with local recurrence [26
In conclusion, we found no evidence to suggest that RALP results in worse oncological outcomes, even for patients with high risk cancer. Differences between surgeons were larger than differences between surgical approaches. Our findings suggest that, if the operation is performed optimally, RALP need not be limited to patients with low to intermediate risk cancer.