ORLANDO—Obesity independently predicts improved survival among patients undergoing radical cystectomy (RC) for muscle-invasive bladder cancer, investigators reported at the American Urological Association 2014 annual meeting.

In a retrospective study of 728 patients who underwent RC (median age 70 years), the median overall survival was significantly longer in obese (body mass index [BMI] of 30 kg/m2 or higher) than non-obese patients (4.6 vs. 2.7 years).

After adjusting for clinical and pathologic characteristics, obese patients had a 40% decreased risk of death compared with non-obese patients, Gautum Agarwal, MD, and colleagues at the H. Lee Moffitt Cancer Center and Research Institute in Tampa, reported.

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The finding of obesity being associated with improved survival has been seen in esophageal and lung cancer as well, Dr. Agarwal told Renal & Urology News.

Obesity was associated with increased operative time (398 vs. 354 minutes for non-obese patients) and increased estimated blood loss (1,045 vs. 926 mL); however,  increased BMI did not result in an increased rate of  blood transfusions or positive surgical margins (PSM).

Other factors that were independently and significantly associated with increased mortality after RC included PSM, tumor stage, nodal status, increased blood transfusions, stage 4 and 5 chronic kidney disease, and a hospital stay longer than 7 days.

“Fat can no longer be viewed as having no function,” said Dr. Agarwal, a urologic oncology fellow. “Rather, it acts like an endocrine organ secreting leptin and adiponectin, which are pro- and anti-inflammatory factors.

“In addition, not all obese patients are the same. There are differences in their metabolic health which may be a cause for the difference in survival.”  Further research to investigate the mechanisms involved are warranted.