Surgical robot makes prostate removal safe for obese men

April 14, 2006

The use of a robotic system could make surgery for prostate cancer an option for thousands of obese men who might otherwise be turned down, report researchers from the University of Chicago in the April 2006 issue of the journal Urology.

The prostate's protected location deep in the pelvis makes surgical treatment for obese prostate cancer patients challenging, even for experienced surgeons. Because profoundly overweight patients often have surgical complications, many physicians advise such patients to postpone the operation until they lose weight--which they seldom do--or to consider radiation therapy instead of surgery.

Using the robotic surgical system, however, to remove a cancerous prostate, "enables us to work under the abdominal wall muscles and fat, avoiding many of the problems that make open prostate surgery so difficult in this group of patients," said Arieh Shalhav, MD, associate professor of surgery at the University of Chicago and director of the study.

The study looked at all 150 men who had a robotic laparoscopic radical prostatectomy by Drs. Shalhav and Gregory Zagaja at the University of Chicago Hospitals between February 2003 and November 2004.

Patients were divided into three groups according to weight. Group one consisted of 39 men with a normal body mass index (BMI) of 25 or less. Group two included 65 overweight men, with a BMI between 25.1 and 30. Group 3 contained 46 obese men with a BMI over 30, including three men over 40 and one over 50.

The only statistically significant differences noted between the groups were that the operation took, on average, 60 minutes longer and blood loss was 70cc (2.4 ounces) higher in the obese patients. Otherwise results were similar for all three groups in terms of complications, hospital stay, cancer control and resumption of urinary control and sexual activity.

"We found," the authors wrote, that this operation "can be completed safely in overweight and obese patients, with results similar to those in a cohort of normal-weight patients."

Overweight men were the quickest to regain urinary continence and sexual function. Six months after treatment, 80 percent of overweight men in this study had full urinary control, compared to about 75 percent of normal or obese men. And six months after surgery 75 percent had normal sexual function, compared to 50 percent of normal weight men and 70 percent of obese men. By 12 months, however, 80 percent of normal-weight men had regained their baseline sexual potency.

The results compared very favorably with previous studies showing that between 40 percent and 75 percent of conventional prostatectomy patients regain their sexual function at one year suffer from postoperative impotence.

"This was a small, single-center study," said Shalhav, "and although we saw differences, it was the similarities that were most noteworthy, and encouraging."

The robotic approach allows the surgeon essentially to bypass the extra tissue that can limit access and impair visualization during open surgery. Instead of making a six-inch-long incision through inches of abdominal fat, which must be held back with retractors, the robotic instruments and camera enter the abdomen through several small holes. Once the surgical tools are in place, the cavity around the prostate is inflated with carbon dioxide and the surgeon has an unobstructed view and room to maneuver.

"We have known for some time that this minimally invasive approach using the da Vinci surgical robot had certain advantages over open surgery for treatment of prostate cancer," Shalhav said. "Patients have less pain, smaller scars, minimal blood loss and rapid recovery. Ninety five percent go home the next day and resume normal activities within a week, compared to three-to-five weeks for those who have open surgery."

"This study shows that we can extend those advantages to men who were not previously considered good candidates for prostate surgery because of their weight. "We now think robotic prostatectomy is the best surgical option for overweight and obese men, who have become the majority of our patients." Almost 75 percent of the men in the study were overweight or obese.

Other than skin cancer, prostate cancer is the most common type of cancer found in American men and the second leading cause, after lung cancer, of cancer death in men. The American Cancer Society estimates that there will be about 234,460 new cases of prostate cancer in the United States in 2006. Almost half of those men will choose surgical removal of the prostate.

At the University of Chicago Hospitals, Intuitive Surgical's da Vinci robotic system is also used for several other urologic applications, as well as by general surgery, cardiac, vascular and thoracic surgeons.

Additional authors of the paper include Albert Mikhail, Benjamin Stockton, Marcelo Orvieto, Gary Chien, Edward Gong, Kevin Zorn and Charles Brendler, all from the section of urology at the University of Chicago.

The study was supported in part by an unrestricted independent medical grant from Pfizer Pharmaceuticals.

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