Volumetric measurement of compensatory hypertrophy in the contralateral normal kidney by the tumor growth

Abstract

Purpose: We evaluated the association between tumor size and preoperative volumetric kidney parameters measured with CT in patients with renal cell carcinoma (RCC).

Methods: We prospectively identified 1118 patients who underwent radical or partial nephrectomy for RCC between 2011 and 2014. Contrast-enhanced CT was performed within three months before surgery. Kidney volume was measured using a tissue segmentation tool program from CT images. We classified patients into three groups depending on tumor size (A: ≤4 cm, B: 4-7 cm, C: >7 cm). The preoperative volumetric kidney parameters were compared and multivariable linear regression was used to analyze potential factors associated with compensatory hypertrophy of the contralateral normal kidney before surgery.

Results: Patients in group C had a significantly larger contralateral normal kidney volume than patients in A and B (A: 170.0 mL, B: 171.7 mL, C: 187.2 mL, p < 0.001). The contralateral kidney volume was not significantly different between groups A and B (p > 0.05). However, tumor-side real kidney volume in group C was significantly smaller than that of groups A and B (A: 168.8 mL, B: 164.9 mL, C: 150.9 mL, p < 0.001). On multivariable analysis, increased contralateral kidney volume was positively associated with male gender, higher BMI, DM, higher preoperative GFR, and tumor size (>7 cm), and negatively associated with older age (p < 0.05). Tumor size had the strongest positive association with contralateral kidney volume (>7 cm, partial regression coefficient = 30.2).

Conclusions: Tumor size (>7 cm) is the strongest factor associated with compensatory hypertrophy in the contralateral normal kidney before surgery.

Keywords: Computerized tomography; Hypertrophy; Nephrectomy; Renal cell carcinoma.