PARIS — Patients with smaller prostate glands were at greater risk of positive surgical margins in a retrospective side-specific study of laparoscopic radical prostatectomies at Memorial Sloan-Kettering Cancer Center in New York.
The finding runs counter to what many surgeons believe, Dr. Fernando P. Secin said in an interview at the annual congress of the European Association of Urology.
In the minds of surgeons, a small gland is an easy case, said Dr. Secin of the department of urology at Memorial Sloan-Kettering. Instead, he reported that a gland weighing less than 30 g was one of seven risk factors identified in the study of 407 patients resected by a single surgeon between October 2002 and April 2005.
The other risk factors were a prostate-specific antigen (PSA) score greater than 10 ng/mL, a biopsy Gleason score of 7 or higher, the presence of bulky disease on endorectal MRI, a palpable nodule, and either multiple positive biopsy cores or a high percentage of tumor on biopsy cores.
Dr. Secin and his coauthors suggested that laparoscopic surgeons might decrease the incidence of positive surgical margins by considering these factors when planning operations.
Neurovascular bundle (NVB) dissection was not found to be a risk factor for positive surgical margins in “adequately selected patients.” The study was the first to evaluate the impact of three degrees of NVB on surgical margins, Dr. Secin said.
Patients were significantly more likely (odds ratio 3.85) to have positive margins with an interfascial NVB than with an intrafascial NVB. Positive margins were more common (odds ratio 1.41) with an extrafascial NVB, but the difference did not reach statistical significance.
Another innovative find in the study was the side-specific analysis that excluded any side of a prostate gland that did not contain cancer. As cancer-free sides would always have a negative margin by definition, including them did not yield information about risk factors in these procedures, Dr. Secin explained.
The investigators excluded 86 of 814 evaluable prostate sides, analyzing a total of 728 sides: 361 right sides and 367 left sides. All told, positive surgical margins occurred in 26 right sides (7.2%) and 33 left sides (9%).
The positive margin rate was highest at the apex and the posterior of the gland. Positive margins also were about twice as likely to occur at the apex when tumors were on the left side of the prostate: 15 cases were on the left side (4.1%) vs. 8 on the right side (2.2%). Posterior margins were similar on both sides: 14 occurred on the right side (3.9%) and 11 on the left (3%), he reported.
Dr. Bertrand D. Guillonneau, senior author and section head of minimally invasive surgery in Sloan-Kettering's department of urology, suggested that smaller glands may have larger tumors proportionally. “The remarkable thing is the smaller the gland, the higher the risk,” he said.
Other risk factors included a PSA level of more than 10 ng/mL and a biopsy Gleason score of 7 or higher. DR. SECIN