In comparing convalescence among patients undergoing either an intraperitoneal or extraperitoneal robotic prostatectomy, the extraperitoneal approach was associated with higher activity and cognitive scores at 6 weeks and higher gastrointestinal scores at 2 weeks based on the CARE questionnaire. We observed similar rates of positive surgical margins and at least as good functional outcomes (i.e., higher urinary irritation/obstruction scores at 3 months) with the extraperitoneal approach.
The extraperitoneal robotic approach, which aims to recapitulate the traditional approach, was first described in 2002.12
Potential advantages of this approach include decreased risk of bowel complications, containment of blood or urine in the extraperitoneal space allowing for tamponade, and minimal Trendelenburg positioning since the peritoneum acts as a natural retractor for the bowel and bladder.11, 12, 21–23
Surgeons learning the extraperitoneal approach who are already adept at using the robot will likely not confront a steep learning curve. In fact, operative times may improve with the extraperitoneal approach due to decreased time needed to create the perivesical working space.11
Potential disadvantages compared to an intraperitoneal approach include a smaller working space, difficulty accessing the pelvis, and tension on the vesicourethral anastamosis.11
To date, three studies have directly compared the extraperitoneal and intraperitoneal approaches for robotic prostatectomy.11, 13, 14
These studies demonstrate that the extraperitoneal approach is feasible with no differences in peri-operative outcomes. However, two of these comparisons involved a relatively small number of patients (i.e., 80 and 55 patients) and did not assess patient-reported outcomes. The most recent study did look at functional outcomes in 155 patients who had undergone an extraperitoneal robotic prostatectomy and found that post-operative pain scores were lower and recovery of continence was faster compared to the intraperitoneal approach.14
In addition to the parameters evaluated in this study, however, we assessed urinary irritative/obstructive symptoms, bowel and hormonal domains, and recovery of activity and cognitive levels after surgery.
Implementing the extraperitoneal approach aims to improve health-related outcomes without compromising cancer control. Initially, there was a concern that the extraperitoneal approach would involve a small working space without good access to the prostate, thus making the dissection of the prostate more tedious and potentially compromising the surgical margin status. However, by using finger dissection and a balloon dilator as well as having well-defined port placements to allow adequate range of motion of the robotic arms, the working space is quite manageable, and the prostate can be dissected freely without having to retract the bowel.11
Among the extraperitoneal and intraperitoneal approaches, our positive surgical margin rates were comparable (p=0.63) at 14% and 10%, respectively. These rates are consistent with those reported in the literature.13–15, 17, 24
As our data matures, biochemical recurrence rates will provide additional feedback on the surgical quality of the extraperitoneal approach.
In addition to surgical margin status, evaluating patient-reported outcomes is useful in comparing these two approaches. Although these outcomes are well-reported in general,25, 26
our study is the first to use both the EPIC and CARE questionnaires in this setting. A few studies have reported adequate erectile function after the extraperitoneal approach as measured by the Sexual Health Inventory in Men questionnaire and have evaluated continence by reporting the need for pads.14–17
However, no studies have described patient-reported outcomes related to bowel, hormonal, or surgical recovery after the extraperitoneal approach.
In this light, we compared patient recovery after the extraperitoneal and intraperitoneal approaches using the CARE questionnaire. No differences in activity level were demonstrated at 2 weeks (p=0.47), but by 6 weeks, patients undergoing the extraperitoneal approach reported higher activity levels (p=0.03) than those undergoing the intraperitoneal approach. We posit that, although similar incisions are made for the two approaches, staying extraperitoneal may quicken recovery and lessen discomfort, resulting in higher activity levels at 6 weeks. The improvement in cognitive scores at 6 weeks (p=0.04) is an interesting finding that may directly relate to the increase in activity level. This observation warrants further investigation. Gastrointestinal recovery followed a different trend; recovery appeared faster with the extraperitoneal approach at 2 weeks (p=0.05), but then abated at 4 and 6 weeks. Although an ileus is likely to resolve by 2 weeks, residual gastrointestinal effects of intraperitoneal manipulation may linger.
In addition to evaluating short-term health status during convalescence, functional outcomes were measured using the EPIC survey. At 3 months, outcomes were similar between the extraperitoneal and intraperitoneal approaches across all domains, except for the urinary irritation/obstructive domain, in which scores were higher for the extraperitoneal group (p=0.03). This suggests that functional outcomes in the short-term are at least as good with the extraperitoneal approach.
There are several limitations to our study. First, patients were not randomized to either the extraperitoneal or intraperitoneal approach, which introduces the possibility of selection bias based on either patient characteristics or surgeon preferences. This is corroborated by the finding that the extraperitoneal approach was associated with lower blood loss and shorter operative time. These factors could influence patient outcomes as well. However, the two cohorts had similar pre-operative demographics such as age, biopsy Gleason score, and prostate-specific antigen levels and a large proportion of the cases were performed by two experienced surgeons who used both the intra- and extraperitoneal approaches and had passed the steep part of the learning curve for both procedures. Second, this study specifically addresses short-term outcomes. While differences in the two surgical approaches are most likely to appear during this period, going forward, it will be important to analyze more long-term endpoints such as biochemical recurrence and complications. Nonetheless, compared to the intraperitoneal approach, the extraperitoneal approach had a similar positive surgical margin rate, which is an independent predictor of biochemical and local recurrence, and the development of metastasis.27
Lastly, the response rate for the EPIC questionnaire was 55%. This is due to the fact that the EPIC survey was completed at the 3-month office visit. Many non-responders either rescheduled this visit or, if referred from an outside urologist, followed-up locally. However, the percent of responders in the extraperitoneal and intraperitoneal groups were similar, and there were no statistically significant differences between EPIC responders and non-responders for demographic or disease-severity measures (data not shown).
Despite these limitations, the findings from this study deserve consideration. Adopting the extraperitoneal approach may provide a way to improve recovery while maintaining adequate cancer control and functional outcomes. A more rigorous assessment of short-term functional outcomes, for example at 1, 2, 3, and 4 weeks post-operatively, may better define the true differences between these two approaches. In addition, studies with longer follow up that evaluate biochemical recurrence rates and complication rates may help elucidate any differences in long-term cancer control as well as in functional and recovery outcomes.