IntroductionThe last decade has seen an increased uptake of the robotic-assisted laparoscopic approach for radical prostatectomies. Despite the negative results of the only published phase III randomized clinical trial comparing robotic-assisted laparoscopic to open radical prostatectomy, which demonstrated no significant differences in short- and medium-term functional outcomes between the two approaches,1 it is currently estimated that more than 70% of radical prostatectomy surgeries performed since 2012 in the United States have been with robotic assistance.2 In 2018, it was estimated that 92.6% of all radical prostatectomies in England were performed using this minimally invasive technique.3
Novel approaches in this field, such as single-port robotic systems and development of the Retzius-sparing approach to radical prostatectomies, have served as further attempts to improve functional patient outcomes. While there will inevitably be ongoing interest in novel surgical approaches, it has long been recognized that characteristics of the surgeon, rather than the procedural approach taken (e.g. minimally invasive versus open), is most influential for patients’ functional and oncologic outcomes. One of the most easily measured surgeon characteristics which, across surgical specialties and procedures, has shown a strong association with patient outcomes is annual case volume and experience. In this Center of Excellence review article, we highlight the current evidence examining the association between a urologist’s volume/experience and oncologic and functional outcomes in patients undergoing radical prostatectomy.
Surgeon Annual VolumeSeveral studies have assessed the association between a surgeon’s annual volume of radical prostatectomies and post-operative outcomes for their patients. Published in The New England Journal of Medicine in 2002, Begg et al. utilized Surveillance, Epidemiology, and End Results–Medicare linked data of 11,522 patients who underwent a radical prostatectomy between 1992 and 1996. Compared to surgeons with low (one to ten cases during the study period) and medium (11 to 19 cases) surgical case volumes, the 159 surgeons in the highest (20 or more cases) volume quartile had significantly lower postoperative (p<0.001) or later urinary complication rates (p<0.001), as well as lower long-term incontinence rates (p<0.001).
A similar report published by Hu et al. in The Journal of Clinical Oncology in 2003 used claims data from a national 5% random sample of Medicare beneficiaries that included 2,292 men who underwent a radical prostatectomy at 1,210 hospitals by 1,788 surgeons in 1997 and 1998. Surgeons were classified as high (≥ 40 per year) or low (< 40 per year) case volume. Compared to low-volume surgeons, high-volume surgeons had significantly lower odds of post-operative complications (Odds Ratio [OR]: 0.53, 95% Confidence Interval [CI]: 0.32 – 0.89) and shorter lengths of hospital stay (4.1 versus 5.2 days, p=0.3).5
These results have been similarly corroborated within the context of Canadian,6 Swedish,7 and English healthcare systems8. In an Ontario-based population analysis of 15,870 men treated with an open radical prostatectomy between 2002 and 2009, it was demonstrated that patients operated on by a high-volume surgeon (≥39 cases/year) had significantly lower hazards of treatment-related hospital admissions (Hazard ratio [HR]: 0.54, 95% CI: 0.47 – 0.61, p<0.0001) and need for urologic procedures (HR: 0.69, 95% CI: 0.64 – 0.75, p<0.0001), compared to those operated on by the lowest volume surgeons (≤15 cases/year).6
Furthermore, an analysis of 9,810 patients who underwent robotic-assisted radical prostatectomy from the National Prostate Cancer Register of Sweden between 2015 and 2018 demonstrated similar results favoring high-volume surgeons. Compared to the lowest volume surgeons (5 – 13 robotic-assisted radical prostatectomies/year), surgeons in the highest volume quintile (>75/year) had significantly increased odds of operative time <150 minutes (OR: 9.20, 95% CI: 7.11 – 11.91) and low operative blood loss of <100 ml (OR: 2.58, 95% CI: 2.01 – 3.21). Moreover, surgeons in the highest volume group had significantly higher odds of performing a nerve-sparing radical prostatectomy (OR: 2.89, 95% CI: 2.34 – 3.57) and of achieving negative surgical margins (OR: 1.90, 95% CI: 1.54 – 2.35) compared to their lower volume colleagues:7
A report from the Hospital Episodes Statistics database, that records data on all National Health Service (NHS) hospital admissions in England, analysed all elective radical prostatectomies performed between January 2013 and December 2018. In this analysis of 35,629 prostatectomies (27,945 of which were performed with robotic-assisted laparoscopy), high surgeon volume was associated with significantly lower odds of 90-day emergency readmissions (OR: 0.82, 95% CI: 0.72 – 0.92, p=0.001) and prolonged hospital length of stay (OR: 0.78, 95% CI: 0.72 – 0.85, p<0.001).8
In 2021, Van den Broeck cet al. published a systematic review of the impact of surgeon radical prostatectomy caseload volume on oncologic outcomes, including positive surgical margins, operative complications, perioperative mortality and urinary incontinence.9 With regards to positive surgical margins, it was demonstrated that high-volume surgeons had lower odds of positive surgical margins with an odds ratio of 0.61 (95% CI: 0.43 – 0.87).10 Steinsvik et al. similarly found that, compared to high-volume surgeons (>50 cases/year), low-volume (<20 cases/year; OR: 3.73, 95% CI: 2.25 – 6.17) and intermediate-volume (20 – 50 cases/year; OR: 1.83; 95% CI: 1.02 – 3.30) surgeons had increased odds of positive surgical margins:11
With regards to other oncologic outcomes, Williams et al. reported significantly lower odds of receiving additional cancer treatment within six months of a radical prostatectomy for very high-volume (open radical prostatectomy: 30 – 91 cases every two years; minimally-invasive radical prostatectomy: 90 – 128 cases every two years) compared to low-volume surgeons (open radical prostatectomy: one to seven cases every two years; minimally-invasive radical prostatectomy: one to 14 cases every two years) with an odds ratio of 0.60 (95% CI: 0.46 – 0.78).12 Hu et al further demonstrated that with each twenty case annual increase in surgical volume, the odds of receiving salvage therapy within six months of a radical prostatectomy is reduced by 8% (odds ratio of 0.92, 95% CI: 0.88 – 0.98).13 With respect to prostate cancer-specific mortality, Bolton et al. reported an increased risk of mortality for patients treated by a low-volume (fewer than eight cases per year) compared to a high-volume (eight or more cases per year) surgeon with a Fine and Gray subdistribution hazard ratio of 1.80 (95% CI: 1.08 – 3.01) after accounting for competing risks of death.13
With regards to operative complications, seven out of eight studies observed a significant reduction in complication rates with increasing surgical annual volume.9 Schmitges et al. reported increased odds of a perioperative rectal laceration for lower-volume surgeons (seven or fewer cases per year) with an odds ratio of 3.26 (95% CI: 1.93 – 5.51) compared to very high-volume surgeons (51 cases per year).15 Low-volume surgeons had 7.38-fold increased odds of open conversion during minimally-invasive radical prostatectomies.16 Based on the currently available data, no firm conclusions could be made about an association between surgeon volume and perioperative mortality rates.9 Long-term incontinence rates, defined as more than one year post-operatively, were significantly lower for very-high volume surgeons (33–121 cases per year) with incontinence rates of 16%, compared to 19–20% for low-, medium-, and high-volume surgeons (p=0.04).17
Given the heterogeneity of the included studies in the systematic review by Van den Broeck et al., no direct comparisons between the operative techniques (open versus robotic) could be made with respect to impact of surgical volume on patient outcomes.9 However, other reviews have concluded that the volume-outcome relationship is relatively consistent for both open and robotic approaches to radical prostatectomy.18
Surgeon ExperienceBeyond annual surgical volume (reflecting recent operative experience), work has shown that increasing overall (ie. lifetime) surgeon experience is associated with improved post-operative outcomes. In an analysis of 1,827 prostate cancer patients treated with a robot-assisted radical prostatectomy, it was demonstrated that greater surgeon experience was associated with decreased odds of a positive surgical margin (p=0.035). The incidence of positive surgical margins improved from 16.7% in surgeons with ten prior procedures to 9.6% in patients operated on by surgeons with 250 prior procedures (risk difference: 7.1%, 95% CI: 1.7 – 12.2). This trend remained consistent in patients with non-organ confined disease, with corresponding probabilities of 38.4% and 24.9%, respectively (absolute risk reduction 13.5%, 95% CI: -3.4 – 22.5).19 An analysis by Klein et al. further demonstrated that surgeon experience was significantly associated with outcomes across all risk groups (p<0.001 for low and intermediate risk; p=0.016 for high risk). The following figure shows the learning curve for cancer control after radical prostatectomy stratified by preoperative risk group showing the predicted probability of freedom from biochemical recurrence at 5 years with increasing surgeon experience in patients with typical cancer severity in each risk group (light gray curves – low risk; medium gray curves – intermediate risk; black curves – high risk; dotted lines – 95% CI):20
Increasing surgeon experience has also been shown to be associated with improved post-operative functional outcomes. In an analysis by Hu et al., increasing surgical experience, in increments of 50 cases, was shown to be associated with improved five-months (EPIC score difference: 5.21, 95% CI: 1.40 – 9.02, p=0.007) and 12-months sexual function score (EPIC score difference: 0.06, 95% CI: 0.00 – 0.12, p=0.061). This analysis suggested that there was an improvement plateau after 250 to 300 cases.21 Further reports, however, have suggested that continued improvements in patient sexual function scores are seen with increasing surgeon experience beyond 1,000 cases.22
Surgeon experience has also been shown to be an independent predictor of urinary continence recovery (hazard ratio: 1.02, p<0.001). The surgical learning curve for urinary continence appears to be similar amongst surgeons, with one-year rates improving from approximately 60% with initial cases to almost 90% after more than 400 procedures.23
Surgeon Feedback and Operative OutcomesWhile there appears to be a clear association between increasing surgeon volume/experience and improved oncologic and functional outcomes, interventions that provide surgeons with outcomes feedback have been evaluated, in an attempt to further improve physician-level outcomes. In 2017, Matulewicz et al. evaluated the efficacy of a comparative quality performance review that aimed at improving positive surgical margin rate at the time of radical prostatectomy, a surrogate of surgical oncology quality. This study included eight surgeons who conducted 1,822 radical prostatectomies over a one-year period (1,392 before and 430 after intervention). Individual surgeons were provided with confidential report cards every 6 months detailing their case mix, case volume and pT2 radical prostatectomy positive surgical margin rates relative to 1) their own self-matched data, 2) the de-identified data of their colleagues and 3) institutional aggregate data during the study period. Positive surgical margin rates were compared before and after the intervention. The aggregated departmental positive surgical margin rates improved from 10.6% pre-intervention to 7.4% post-intervention. Analysis adjusting for higher risk cancer in the post-intervention group demonstrated consistent improvements post-intervention (OR: 0.64, 95% CI: 0.43 – 0.97, p = 0.03). All five surgeons with positive surgical margin rates higher than the aggregate department rate in the pre-intervention period showed improvements post-intervention.24
However, a similar intervention by Kumar et al. in 422 patients undergoing radical prostatectomies by eight surgeons demonstrated conflicting results. Following administration of an individual feedback report card, nerve sparing surgery increased from 70% pre-intervention to 82% post-intervention (p=0.01). This was accompanied by an increase in the proportion of patients with a positive surgical margin post-intervention: 39% versus 31% pre-intervention (p=0.08). There was no difference in postoperative erectile function (17% versus 18%, p=0.7) and a decrease in continence (75% vs 65%, p=0.02) one year postoperatively. These results suggested that the provision of surgical report cards does not improve functional or oncologic outcomes in this setting:25 However, these data also reflect the inevitable trade-offs inherent in performing radical prostatectomy: actions which serve to increase rates of nerve sparing are likely to also increase rates of positive surgical margins. Importantly, this work from Kumar and colleagues suggests that the increased utilization of nerve sparing did not improve rate of post-operative erectile function meaningfully.
ConclusionWhile definitions vary between studies, there is consistent evidence of a clear association between increasing surgeon radical prostatectomy volume/experience and improved perioperative, oncologic, and functional outcomes in prostate cancer patients. Beyond patient outcomes, the centralization of prostate cancer care may offer health system benefits though this must be considered in the context of access to care.
- Rashid K. Sayyid, MD, MSc, University of Toronto, Toronto, Ontario
- Zachary Klaassen, MD, MSc, Medical College of Georgia, Augusta, Georgia, USA