Positive margins and their significance

UroToday – Prognostic Significance of Location of Positive Margins in Radical Prostatectomy Specimens

In the 201 men with a single positive SM, it was found in the apex in 75 men (37%), posterolateral in 70 men (35%), bladder neck in 20 men (10%), anterior in 25 men (12%), posterior in 11 men (5%), and in no men was a single positive SM found in the seminal vesicle. The positive SM rate decreased with time, from 18% in the early cohort versus 10% in the late cohort. Those with a positive SM had a 1.4 fold greater risk of progression than those with a negative SM (HR 1.39). In the multivariable analysis, significant differences were found between the effects of different sites of a positive SM on disease progression. A positive SM at the posterolateral or posterior regions significantly increased a patients’ risk of progression for a positive SM versus no SM at these sites. The authors attribute the posterolateral and posterior positive SM rates to neurovascular bundle preservation and an inherent risk of a nerve sparing operation.

This study out of Memorial Sloan Kettering reveals that there is a 40% increase in the recurrence rate of prostate cancer after surgery for a positive margin. The worst positive margins are in the area where the nerve bundles are.

Positive Margins in Laparoscopic prostatectomy

UroToday – European Urology – Preoperative and Intraoperative Risk Factors for Side-Specific Positive Surgical Margins in Laparoscopic Radical Prostatectomy for Prostate Cancer

beige_quote.bmpSuspected ECE on endorectal coil MRI had neither protective effect nor increased risk for PSMs, which means that, whereas this variable may help with surgical planning, its capacity to decrease PSM rates remains to be prospectively investigated. Although increasing BMI may impact PSMs [17], we did not find such an association, possibly because individuals with high BMI were underrepresented. Of the 407 patients, 79 had a BMI between 30 to 35, and only 10 had a BMI >35.
It is well established that tumour volume is associated with higher PSM rates [1], [12] and prostate biopsy data may help to predict tumour volume and risk of a PSM. Although overall percentage of cancer in the biopsy specimen (total millimeters of cancer in the biopsy specimen divided by total millimeters of biopsy tissue) is a more accurate predictor of cancer volume, we used the maximum percentage of cancer in any core of the specific side because not all prostate biopsies were done at our institution. Of interest, 201 (28%) of the 728 prostate sides that harboured cancer had a negative ipsilateral preoperative biopsy. A PSM was identified in 4% of them, compared with an 8% PSM rate among the 527 prostate sides with a positive biopsy. In other words, surgeons should not become overconfident about dissecting the NVB extremely close to the prostate side where the biopsy was negative.

This was an excellent paper that made several observations that I have seen as well:
Smaller prostates tend to have a higher level of positive margins.

Positive margins often happen on sides where there is no cancer on biopsy.
I do not personally order preoperative MRIs, but this showed it did not make a statistical difference in positive margin rates. I would be curious to see how many of the patients with preoperatively suspicious MRIs for extracapsular extension actually had it at the time of surgery.

Positive margins after partial nephrectomy

UroToday – Positive Surgical Parenchymal Margin After Laparoscopic Partial Nephrectomy for Renal Cella: Oncological Outcomes Carcinom

beige_quote.bmpThursday, 15 March 2007
BERKELEY, CA (UroToday.com) – Positive margins following supposedly curative surgery can be devastating for patient and surgeon alike.
The implication that cancer was “left behind” implies a continued biologic threat, although little is known about the impact of positive margins following nephron sparing surgery, because, thankfully, it is a rare finding. Here, two leaders in laparoscopic renal surgery (Gill and Kavoussi) combine their experience to examine oncologic outcomes in patients undergoing laparoscopic partial nephrectomy found to have positive surgical resection margins.

These 2 surgeons are among the best in the world in minimally invasive partial nephrectomy. I would think that there margins were very close to being negative and management should be dictated by close followup of these patients if the surgeon felt he had removed the whole tumor. It is certainly a controversial topic.

Improvement in positive margins with robotic surgery

Robotic Prostatectomy can reduce positive margins
Source- Surgery News p. 13
This was an abstract presented at SLS meeting in Boston in September.
The 2 urologists showed a dramatic improvement in positive margins from their last 100 prostatectomies done open to the first 93 done robotically.
The organ confined changes for each surgeon were 37% and 27.5% for their last open ones to 5.7% and 8% for their first robotic ones.
This is a study that showed a drastic improvement in margins for private practice urologists.
My questions would be if these patients were comparable.
Their open margin rate seems well above national averages and they had better than expected results for their fist 50 patients. Most surgeons see an increase in positive margins when they first start robotics.
I did not track my open results, but I would guess the organ confined results were in the 15% for open. My first 70 patients had a 20% positive margin rate for organ confined disease and the last 100+ have been under 5%. I also have performed all prostatectomies robotically and have not turned down anyone for surgery based on amount of cancer.