The value of sex-specific abdominal visceral fat as measured via CT as a predictor of clear renal cell carcinoma T stage

Abstract

Although much is known about how adipose tissue affects the development of clear cell renal carcinoma (ccRCC), little information is available for the utility of sex-specific abdominal visceral fat composition as a predictor of clear cell renal carcinoma (ccRCC) T stage. We conducted CT-based sex-specific abdominal fat measurements in ccRCC patients to assess whether VFA distribution could predict the ccRCC T stage. In total, 253 patients (182 males and 71 females) from our hospital with pathologically confirmed ccRCC (178 low T-stage and 75 high T-stage) were retrospectively reviewed for the present study. Computed tomography (CT) scans were assessed using ImageJ to differentiate between the visceral and subcutaneous fat areas (VFA and SFA), after which the relative VFA (rVFA) and total fat area (TFA) were computed. The relationships between these fat area-related variables, patient age, sex, and BMI, and ccRCC T stage were then evaluated through univariate and multivariate logistic regression analysis to clarify the association between general or sex-specific abdominal visceral fat and T stage. Following adjustment for age, males with high T stage ccRCC exhibited an increased rVFA as compared to males with low T stage ccRCC, with the same relationship being observed among females. This association between rVFA and high T stage was confirmed through both univariate and multivariate models. As thus, sex-specific visceral fat composition is a reliable independent predictor that can identify both male and female patients with high T stage ccRCC.

Keywords: Clear renal cell carcinoma; T stage; abdominal; computed tomography; obesity.

Figure 1.

Fat measurements on CT. Subcutaneous fat (SFA, purple area) and Visceral fat (VFA, red area) were segmented after outlines (yellow line) were placed in the abdominal skeletal muscle from the original CT image for automatic calculation

Figure 2.

Representative radiographic and histological images of patients. (a-c) Low-T-stage ccRCC in a 49-year-old woman. (d-f) High-T-stage ccRCC in a 54-year-old woman. (a) Enhanced CT showing right renal tumour (white arrow). (b) CT image with a relative visceral fat area (rVFA) of 18.2%. (c) Histologic photomicrograph confirming that the tumour did not involve capsule so as to be T1 stage. (d) Enhanced CT showing right renal tumour (white arrow). (e) CT image with a relative visceral fat area (rVFA) of 35.0%. (f) Histological micrographs confirming that the tumour involved the capsule, but was confined to the perirenal fascia so as to be T3 stage

Figure 3.

The relative visceral fat area (rVFA) was significantly different in both males (a) and females (b) based on T stage

Figure 4.

Comparisons of ROC curve analysis for univariate and multivariate models. Both the rVFA in males (blue solid line) and females (black dotted line) demonstrated good predictive power. In multivariate model incorporating age, good predictive power of rVFA was also observed irrespective of sex