Obesity currently affects 78.6 million people (33%) in the US. Obesity is defined as a BMI of 30 or above. Figure 1 demonstrates the alarmingly high rates of obesity across the US.
Figure 1 – Obesity Rate by State:
Obesity has been shown to harbor 2.3 times higher risk of developing renal cell carcinoma, in patients with a BMI>35.1 In a large meta-analysis of over 464 studies with more than 18000 patients, obesity was demonstrated to be a harmful risk factor for renal cell carcinoma, with a higher disease incidence and more aggressive disease.2 Approximately 40% of renal cell carcinoma patients will be obese. In experienced hands, robotic partial nephrectomy is safe for obese patients, with slightly higher rates of blood loss.3 The robotic approach is gradually becoming the standard of care for partial nephrectomy, even in obese patients.
In obese people, the amount of fat around the kidney is larger, and the amount of toxic or sticky fat is more significant as well. Nephrometry scoring systems assess the technical complexity of the partial nephrectomy. The problem with the R.E.N.A.L and Padua scoring systems is that they are solely based on tumor characteristics and ignore other patient features like obesity and toxic fat.
The Mayo adhesive probability score had been developed (ranging from 0-100), which is capable of predicting the presence of adherent toxic fat.4 A score of 2 or above has been shown to accurately predict the presence of adherent fat. The presence of this adhering fat has also been shown to be correlated with higher operative time, higher intraoperative fat dissection difficulty, and greater intraoperative blood loss.5
Dr. Shalhav concluded his talk, with some important take-home message regarding obese patients with toxic fat. First, it is advisable to plan for a long day in the OR, anticipate more blood loss, place ports about skeletal landmarks, and finally, add as many 5mm ports as needed for retraction. The fat should be dissected of the surgical target, and it should be removed with the specimen. Most importantly, ask for help from the most experienced robotic surgeon, if needed.
Presented by: Arieh Shalhav, MD, Professor of SurgeryChief, Section of Urology, Director, Minimally Invasive Urology, Director, Robotic Surgery, The University of Chicago, Illinois
Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre @GoldbergHanan at 2019 3rd Annual North American Robotic Urology Symposium (NARUS), February 8-9, 2018 - Las Vegas, Nevada, United States
References:
1. Macleod LC et al. Risk factors for renal cell carcinoma in the VITAL study. J Urol. 2013 Nov;190(5):1657-61.
2. Al-Bayati O et al. Urol Oncol 2018
3. Isac WE et al. BJUI 2012
4. Davidiuk AJ et al. Mayo adhesive probability score: an accurate image-based scoring system to predict adherent perinephric fat in partial nephrectomy.
Eur Urol. 2014 Dec;66(6):1165-71.
5. Chessa F et al. 33EAU abstract