Robotic surgery and risk for positive surgical margins
Posted Sep 28 2008 1:49pm
So-called “positive surgical margins” or PSMs are associated with an increased risk for biochemical recurrence of prostate cancer post-surgery and can also be responsible for a significant degree of patient anxiety. Liss et al. have recently sought to determine the specific risks for positive surgical margins in patients undergoing robot-assisted laparoscopic radical prostatectomy (RALP).
The authors defined a PSM as “the presence of cancer adjacent to the inked margin” in the pathological specimen removed by the surgeon. Between November 2003 and March 2007, 216 consecutive patients received a RALP, carried out by a single, fellowship-trained urological oncologist. The pathological specimens were fixed and processed using standard techniques, and assessed by a pathologist at the same institution. A PSM was defined as the presence of cancer adjacent to the inked margin. The patients’ clinical charts were reviewed retrospectively under an approved institutional review board protocol. All available data were used to analyze the patients’ clinical, pathological, and technical risk factors for PSMs.
It should be understood that the results of this study are inevitably specific to this individual surgeon. They can not necessarily be generalized to other urologic oncologists. However, with that proviso, the results of this study were as follows:
The overall prevalence of PSMs was 14.8 percent (32/216), and 5.4 percent (8/149) for stage pT2 cancers.
The only preoperative factors associated with increased risk for a PSM were the patients’ PSA levels (P = 0.012) and PSA densities (P = 0.005). Age, clinical stage, and clinical (biopsy) Gleason grade were not predictors of a PSM.
The overall and pT2 PSM rate remained constant throughout the series of 216 patients (P = 0.371), indicating that initial experience with RALP was not associated with a significantly greater risk of a PSM.
There was a small independent “learning curve” effect, with a lower rate of PSMs associated with each increment of 25 patients, supported by the significantly decreasing trend in PSM for pT3 cancers over time (P = 0.031).
There was no significant increase of PSMs over time with the use of an endostapler to control the dorsal venous complex (DVC); however, there was a significant learning effect, with a decrease in the PSM rate specifically in pT3 cancers using the suture technique (P = 0.005).
A nerve-sparing procedure increased the risk for PSMs (P = 0.03).
Pathologic stage and pathologic Gleason grade were the strongest predictors for PSMs (P < 0.001).
LIss et al. conclude that “the most important risk factors for a PSM after RALP are the preoperative PSA level, PSA density, pathological stage, and Gleason grade.” PSM rates for this surgeon in his initial experience with RALP appear to be comparable to those for a surgeon experienced in the use of RALP. Again, for this surgeon, use of the Da Vinci stapling device to control the DVC did not appear to increase the risk of a PSM, although nerve-sparing did increase the rates of PSM in patients with extraprostatic prostate cancer.
In an editorial comment on this study, on UroToday, Evans states that, “Interestingly, the learning curve for this surgeon regarding PSM was less severe that the surgeon who established the robotics program at their institution. This suggests that once a robotics program is established, the learning curve for subsequent surgeons will benefit from the program in place.” While this may be the case, The “New” Prostate Cancer InfoLink would add that the inherent skill of the individual trainee is undoubtedly also a key factor. Other surgeons may not be able to learn as well or as quickly as this individual clearly did.