A comparison of radiologic tumor volume and pathologic tumor volume in renal cell carcinoma (RCC)

To investigate the difference between preoperative radiologic tumor volume (RTV) and postoperative pathologic tumor volume (PTV) in patients who received nephrectomy for renal cell carcinoma (RCC).

We reviewed 482 patients who underwent preoperative computed tomography (CT) within 4 weeks before radical or partial nephrectomy for renal cell carcinoma. RTV measured by a three dimensional rendering program was compared with PTV (π/6 x height x length x width) measured in surgical specimen according to pathologic tumor size and histologic subtype. Correlation of the inter-quartile range (IQR) of the RTV and Fuhrman nuclear grade was also investigated.

There was a significant positive linear correlation between RTV and PTV (p < 0.001, r = 0.911), and the mean RTV and mean PTV were not significantly different (79.0 vs 76.9 cm3, p = 0.393). For pathologic tumor size (PTS) < 4 cm, the mean RTV was larger than the mean PTV (10.9 vs 7.1 cm3, p < 0.001). For a PTS of 4-7 cm, the mean RTV was larger than the mean PTV (56.0 vs 44.7 cm3, p < 0.001). However, for a PTS ≥ 7 cm, there was no statistical difference between RTV and PTV (p > 0.05). Among patients with clear cell RCC, the mean RTV was significantly larger than the mean PTV (p = 0.042), not for non-clear cell group (p = 0.055). As the quartile of the RTV increased, the Fuhrman grade also increased (p < 0.001).

RTV was correlated with PTV and pathologic grade. RTV was larger than the PTV for a tumor size 7 cm or less or in clear cell RCC. RTV may be useful to measure tumor burden preoperatively.