Contemporary Perioperative Morbidity and Mortality of Minimally Invasive Versus Open Partial Nephrectomy in Obese Patients with Kidney Cancer - Beyond the Abstract

Worldwide, renal cell carcinoma (RCC) represents the sixth most frequently diagnosed cancer in men and the 10th in women, accounting for 5% and 3% of all oncological diagnoses, respectively.1 In the United States, a proportion of the increased incidence of RCC can be attributed to obesity as 42% of these diagnoses could be causally linked to obesity.2 Furthermore, each unit increase in body mass index (BMI) leads to a 1.07 increase in the relative risk of developing RCC.3 Most of RCCs that are found incidentally are smaller (averaged 5.7 cm vs. 8.7 cm) and more often treated with partial nephrectomy (PN) than symptomatically discovered RCCs (15.2% vs. 1.2%).4

PN can be performed either with open or with minimally invasive surgery, which includes laparoscopic (LPN) or robotic (RPN) approach. When comparing oncological outcomes for minimally invasive PN (MIPN) versus open PN (OPN), they were found to be equivalent (p=0.47) with 97.5% and 97.3% cancer‐free survival at 7 years respectively.5 The current American Urological Association (AUA) guidelines recommend PN for clinical T1a RCC. However, these guidelines do not provide urologist concrete tools for determining when to perform an OPN or MIPN.

Considering the increased prevalence of obesity and the increased risk of RCC within this population, determining the risks and benefits of MIPN vs. OPN in an obese patient will be an increasingly more common question posed in urologic practice. Obesity also poses technical and physiologic challenges that make the postoperative period more complicated. In our study, we aimed to compare perioperative morbidity and mortality in obese patients who underwent MIPN (laparoscopic and robotic) vs. OPN.

We used the data from 2008‐2016 of the American College of Surgeons National Surgical

Quality Improvement Program (ACS‐NSQIP). We identified obese patients who underwent either MIPN or OPN. Patient demographics, comorbidities, operative time (OT), length of stay (LOS) and 30‐day postoperative complications, readmissions and mortality were recorded and compared between the two groups. Multivariable logistic regression analysis was used to determine the adjusted odds of early postoperative complications in MIPN vs. OPN.

A total of 9,105 obese patients received PN were included. Of whom, 6,041 (66%) received

MIPN and 3,064 (34%) received OPN. The mean age of the entire cohort was 57.9±11.7 years and the mean BMI was 36.1±5.8 Kg/m2. The most common comorbid conditions were hypertension (68%) and diabetes (27.3%). Compared to the OPN group, patients in the MIPN group had lower ASA class III (59.3% vs. 63.4%), and less likely to have preoperative diabetes, chronic obstructive airway disease or renal insufficiency/dialysis (P<0.05). Mean OT (minutes ± SD) was longer for MIPN vs. OPN (197.2 ± 71.0 vs. 189.6 ± 82.4, p<0.001) while mean LOS (3.8 ± 2.8 vs. 5.8 ± 3.5 days, p<0.001) and 30‐day complications (8.5% vs. 19.8%, p<0.001) were lower. No difference in 30‐day postoperative mortality between MIPN (0.4%) and OPN (0.5%) was observed (p=0.426). In the adjusted analysis, the odds of any complication within 30 days in MIPN group was 61% lower, blood transfusion was 73% lower, pneumonia was 38% lower, sepsis was 70% lower, acute renal failure was 64% lower, superficial surgical site infection was 40% lower and reoperation was 47% lower, compared to OPN patients.

We acknowledge the limitations of our study being retrospective and non‐randomized.

Also, due to the unavailability of information about patient’s tumor characteristics (e.g. nephrometry score), we were unable to account for them in our study. However, the NSQIP database is the largest dataset reporting on perioperative outcomes in North America. It is regularly used to report and compare perioperative outcomes among surgical procedures and different subsets of patients with excellent inter‐rater variability.

Written by: Mahmoud I. Khalil, MD, Rodney Davis, MD, Omer A. Raheem,1 MD, and Mohamed H. Kamel, MD, FACS Department of Urology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, 1Department of Urology, Tulane University, New Orleans, Louisiana

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  2. Calle EE, Kaaks R. Overweight, obesity and cancer: epidemiological evidence and proposed mechanisms. Nature reviews Cancer. 2004 Aug;4(8):579-91.
  3. Bergstrom A, Hsieh CC, Lindblad P, Lu CM, Cook NR, Wolk A. Obesity and renal cell cancer--a quantitative review. Br J Cancer. 2001 Sep 28;85(7):984-90.
  4. Patard JJ, Rodriguez A, Rioux-Leclercq N, Guille F, Lobel B. Prognostic significance of the mode of detection in renal tumours. BJU Int. 2002 Sep;90(4):358-63.
  5. Lane BR, Gill IS. 7-Year Oncological Outcomes After Laparoscopic and Open Partial Nephrectomy. J Urology. 2010 Feb;183(2):473-9.
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