Study: Robotic prostatectomy safe in obese patients

November 1, 2009

Robotic prostatectomy in morbidly obese men is feasible, reasonably safe, and appears to provide oncologic control comparable to that achieved in a normal weight population.

Key Points

Detroit-Robotic prostatectomy in morbidly obese men is feasible, reasonably safe, and appears to provide oncologic control comparable to that achieved in a normal weight population, report researchers from the Vattikuti Urology Institute at Henry Ford Hospital System, Detroit.

In an analysis comparing 226 men who were morbidly obese and 615 controls, the morbidly obese men had significantly larger prostates (53.4 vs. 44.9 grams) as well as worse disease characteristics based on Gleason sum (6.8 vs. 6.2) and proportion of patients with extracapsular disease (41% vs. 22%).

In addition, the morbidly obese patient group's procedures took almost 30 minutes longer considering both operative time and console time (p≤.009 for all comparisons), the researchers found.

However, complications did not appear to be increased in the morbidly obese group, and after a mean follow-up of 83 weeks, the biochemical recurrence rate was similar in the normal weight and morbidly obese patients (2.8% vs. 3.9%; p=.10).

"Several studies have reported radical prostatectomy is technically more difficult in morbidly obese men than in normal weight individuals as well as associated with more complications and perhaps worse oncologic outcomes," said first author Ramgopal K. Satyanarayana, MD, a urology fellow working with Mani Menon, MD, and colleagues.

"However, we were not aware of any information on how the morbidly obese fare with robotic prostatectomy.

"Our operative time results reflect that the robotic procedure is also more technically challenging in the morbidly obese. Based on the data available so far, this study indicates they can achieve favorable outcomes undergoing robotic prostatectomy even though they are likely to have larger glands and worse disease. However, longer follow-up is needed to better determine cancer control."

Patients were identified for inclusion in the study from a consecutive cohort of 4,002 men who underwent robotic prostatectomy at the Vattikuti Institute between September 2001 and September 2008. For the purpose of the study, the NIH definition of morbid obesity was used: body mass index of 35 or higher with one comorbidity or BMI ≥40. The control group included men with a BMI ≤25.

Among the 226 men in the morbidly obese group, 40 met the definition based on BMI ≥40. The most common comorbidities in the morbidly obese group were hypercholesterolemia, diabetes, hypertension, and coronary artery disease.

Greater blood loss

The safety data showed blood loss was significantly higher in the morbidly obese group compared with the controls (183 vs. 137 mL; p<.001). However, there was no difference between groups in required transfusions. Three morbidly obese men and five controls were readmitted to the hospital for postoperative complications.

"The morbidly obese are more susceptible to anesthesia-related risks, especially when the patient is placed in the Trendelenburg position. Fortunately, in our cohort of 226 men, no such problems were encountered," Dr. Satyanarayana told Urology Times.

There were also no statistically significant differences between groups in overall continence rates (>95% in both groups). However, a clinically significant difference was found in the average time to continence, which was about 4 weeks longer in the morbidly obese group, Dr. Satyanarayana said.