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Objective:
Obesity rates have gradually increased throughout the years and correlate with cancer development, including renal cell carcinoma (RCC). Body mass index (BMI) fails to account for variables such as muscle mass or bone structure and measuring body fat on computed tomography (CT) likely provides a more precise assessment of body composition. Prior studies have found associations between adiposity measurements and surgical complications, including partial nephrectomy and have found that visceral adipose tissue (VAT) and VAT area percentage (i.e., VAT/ (VAT + subcutaneous adipose tissue [SAT]) x 100) correlate with clear cell RCC Fuhrman nuclear grade and tumor (T) stage. Our study's purpose was to evaluate if sex-specific measurements of VAT and SAT area on CT correlate with T stage and surgical outcomes in patients with renal masses treated with robotic-assisted partial nephrectomy (RAPN).

Materials and Methods:
IRB approved retrospective review of patients who underwent robotic-assisted laparoscopic partial nephrectomy for a renal mass (2019 - 2021) and had an abdominal or abdominopelvic CT before surgery. VAT and SAT area were measured on CT at the mid L3 level using the Aquarius iNtuition automated tool, with manual correction when necessary. Patient demographics and surgical metrics were collected from the electronic medical record. The Wilcoxon-rank sum test was used to compare the VAT and SAT between the different pathology stages. Surgical metrics and preoperative characteristics were analyzed through a single variable linear and logistic regression model to correlate post-operative outcomes between the sex-specific abdominal fat measurement.

Results:
Study included 135 patients with 114 malignant masses (94 T1a; 19 T1b/T2/T3a). Male (M) patients (n=93) had significantly higher VAT (270 cm^2 vs 150 cm^2, p < 0.001) while female (F) (n=42) had significantly higher SAT (271 cm^2 vs 186 cm^2, p < 0.001). No significant difference in pathology stage T1a vs combined T1b/T2/T3 from VAT percentage in F (33.3% vs 41.1% p > 0.05) or M (54.3% vs 53.6% p>0.05). Sixteen patients had a postoperative complication (F=5,M=11). A doubling of male VAT resulted in an estimated increase in length of stay (LOS) by 0.4 days [95% confidence interval (CI) 0.0-0.8 days, p = 0.034]. No other significant associations of VAT or SAT with outcomes in males or females. Though not significantly different, male patients had higher odds ratio (OR) for any postoperative complications with VAT (OR 1.72, 95% CI 0.77-4.64) and SAT (OR 2.19, 95% CI 0.80-6.94), in contrast to lower OR in female patients (VAT OR 0.64, 95% CI, 0.29-1.431; SAT OR 0.44, 95% CI, 0.13-1.31).

Conclusion:
We observed a small LOS increase with increased VAT in males, and trends for increased female VAT with higher T stage that warrant further investigation. Including patients undergoing total nephrectomy will include more patients with higher stage tumor. Adding VAT measurements to CT already obtained for diagnosis of renal masses may provide additional information for treatment planning and risk assessment.