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

Figures & data

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

Table 1. The baseline characteristics and fat measurements of patients stratified by T stage

Variable	Total (n = 253)	T12 (n = 178)	T34 (n = 75)	p	p*
Age, year	59.63 ± 10.75	57.97 (10.86)	63.56 (9.43)	<0.001^a
Sex, n (%) Female
	71 (28.06)	59 (33.15)	12 (16.00)	0.009^b
Male	182 (71.94)	119 (66.85)	63 (84.00)
BMI	25.50 ± 3.92	25.64 ± 3.83	24.38 ± 4.60	0.293^a	0.441^d
VFA, cm^2	143.91 ± 64.32	136.74 ± 60.76	160.94 ± 69.57	0.010^a
SFA, cm^2	185.70 ± 78.67	195.04 ± 79.88	163.53 ± 71.43	0.004 ^c
TFA, cm^2	329.61 ± 120.58	331.78 ± 116.52	324.47 ± 130.38	0.675^a
rVFA, %	43.61 ± 10.48	41.11 ± 10.51	49.55 ± 7.69	<0.001 ^c	<0.001^d

p< 0.05 is indicated by boldface

^aStudent’s t-test; ^bChi-squared test; ^cMann–Whitney U test; ^dGeneral Linear Model; *adjusted p value

ccRCC: clear cell renal cell carcinoma; BMI: body mass index; VFA: visceral fat area; SFA: subcutaneous fat area; TFA: total fat area; rVFA: relative visceral fat area

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

Table 2. Univariate and multivariate models for predicting ccRCC T stage

	Univariate analysis		Multivariate analysis
	OR (95% CI)	p	OR (95% CI)	p
Total (n = 253)
Age, years	1.055 (1.026–1.087)	<0.001	1.050 (1.018–1.084)	0.002
Sex, female	0.384 (0.185–0.746)	0.007	0.946 (0.394–2.210)	0.900
BMI, kg/m2	0.915 (0.790–1.046)	0.214
VFA, cm2	1.006 (1.002–1.010)	0.007	0.992 (0.976–1.008)	0.313
SFA, cm2	0.994 (0.990–0.998)	0.004	1.006 (0.991–1.020)	0.448
TFA, cm2	0.999 (0.997–1.002)	0.659
rVFA, %	1.103 (1.067–1.145)	<0.001	1.154 (1.037–1.294)	0.011
Male (n = 182)
Age, years	1.050 (1.019–1.085)	0.002	1.046 (1.013–1.083)	0.007
BMI, kg/m2	0.910 (0.774–1.053)	0.225
VFA, cm2	1.004 (0.999–1.008)	0.118
SFA, cm2	0.996 (0.991–1.001)	0.102
TFA, cm2	1.000 (0.997–1.002)	0.975
rVFA, %	1.100 (1.054–1.153)	<0.001	1.097 (1.050–1.151)	<0.001
Female (n = 71)
Age, years	1.098 (1.019–1.207)	0.028	1.064 (0.979–1.178)	0.179
BMI, kg/m^2	0.884 (0.513–1.268)	0.559
VFA, cm^2	1.015 (1.001–1.031)	0.049	1.000 (0.981–1.019)	0.968
SFA, cm^2	0.994 (0.985–1.002)	0.166
TFA, cm^2	0.999 (0.993–1.005)	0.763
rVFA, %	1.131 (1.045–1.245)	0.005	1.109 (1.008–1.239)	0.045

p< 0.05 is indicated by boldface

ccRCC: clear cell renal cell carcinoma; BMI: body mass index; VFA: visceral fat area; SFA: subcutaneous fat area; TFA: total fat area; rVFA: relative visceral fat area

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