Visceral Adiposity at Diagnosis Correlates with Tumor Size and Metastatic Progression in Clear Cell Renal Carcinoma

A Shuster, MD (1), M Patlas, MD (1), S.A Hiltz, MD (2), A Kapoor, MD (2), J.H Pinthus, MD, PhD (3)

Introduction

Renal cell carcinoma (RCC), the most common type of kidney cancer in adults, accounts for 85%-90% of all kidney tumors, and for approximately 3% of adult malignancies. RCC ranks as the 9th leading cause of cancer mortality in western industrialized countries.

Obesity is an established risk factor for renal cell carcinoma (RCC).

The visceral adipose tissue (VAT) is an endocrine active fat compartment and an accurate predictor of obesity related morbidity.

Objectives

To analyze the effect of visceral adiposity in RCC patients at presentation on their disease characteristics and progression.

Materials and Methods:

Prospective data base of 140 patients with clear cell RCC (97 males and 43 females) have been collected over a 3-year period.

All patients had computed tomography (CT) scan at diagnosis available for analysis and underwent either radical or partial nephrectomy.

Visceral, subcutaneous and total adipose tissue volumes have been obtained from 3 representative axial slices at 3 fixed levels (L2 vertebral body, umbilicus and anterior superior iliac spine), using software: ClearImage Demo Version 2.1.12 (Inlite Research, Inc. 2007). Tissue of fat density was defined within -250 to -30 Hounsfield Units. A ratio of visceral adipose tissue to total adipose tissue (%VAT) was then calculated across 3 slices.

Subcutaneous Fat

(highlighted)

Visceral Fat (highlighted)

Original axial slice. Right-

sided RCC is seen (arrows)

Total fat is extracted

Results

Mean age, tumor size and %VAT were 59.5, 5.54cm and 41.4% respectively.

Male patients had significantly higher mean %VAT then female (46.1 and 30.7, p<0.001)- Fig 1, and larger tumor size (5.93cm vs. 4.66cm p=0.03), but almost the same percentage of metastasic cases (26% and 28% respectively).

%VAT was also appreciably higher in metastatic as compared to non-metastatic cases (36% vs. 28.63% p=0.005) but only in female patients. Fig 2

Conclusion

Greater percentage of VAT correlated with clear cell RCC larger than 3cm in all patients.

Greater percentage of VAT correlated metastatic progression in female patients.

Department of Diagnostic Imaging, Hamilton General Hospital (1), and Departments of Surgery-Urology, St. Joseph’s Healthcare Hamilton (2), and Juravinski Cancer Centre (3), Faculty of Health Sciences, McMaster University

Patients with tumors larger than 3 cm had significantly

higher %VAT than those with smaller tumors – Fig 3

(43.6% vs.35.1%, p= 0.0001).

Correlation between VAT% and Tumor Size

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Size (cm)

VA

T%

43.6 35.143.2 38.743.4 39.5

051015202530354045

VAT%

123

Tumor <5 cm> Tumor <4 cm> Tumor <3 cm>

VAT% distribution in RCC patients due to tumor size

30.7

46.1

0

10

20

30

40

50

VAT%

Distribution of VAT% in Genders

Females

Males

*p= 0.0001

36.07

28.63

10

15

20

25

30

35

40

VAT%

Distribution of VAT% in Females with and without Mets

Without Mets

With Mets

* p=0.005

Fig 1

Fig 2

*

Fig 1

*

Fig 3

Note: more linear correlation exists between %VAT and

tumor size< 4cm