Accuracy of multi-detector computed tomography (MDCT) in staging of renal cell carcinoma (RCC): analysis of risk factors for mis-staging and its impact on surgical intervention.

Objectives: To assess the accuracy of multi-detector computed tomography (MDCT) in preoperative staging of renal cell carcinoma (RCC) and to detect the possible risk factors for mis-staging. In addition, the impact of radiological mis-staging on surgical decision and operative procedures was evaluated.

Materials And Methods: Data files of 693 patients, who underwent either radical or partial nephrectomy after preoperative staging by MDCT between January 2003 and December 2010, were retrospectively reviewed. Radiological data were compared to surgical and histopathological findings. Patients were classified according to 2009 TNM staging classification. Diagnostic accuracy per stage and its impact on surgical intervention were evaluated.

Results: The overall accuracy was 64.5%, and over-stage was detected in 29.5% and under-stage in 6%. Sensitivity and specificity were highest in stage T3b (85 and 99.5%, respectively), while T4 showed the lowest sensitivity and PPV (57 and 45%). Degree of agreement with pathological staging was substantial in T1 (κ = 0.7), fair in T2 (κ = 0. 4), perfect in T3b (κ = 0.81), and slight for the other stages (κ = <0.1). On multivariate analysis, conventional RCC and tumor size > 7 cm represent the significant risk factors (RR: 1.6, 95% CI: 1.1-2.3, P < 0.004 and RR: 2.4, 95% CI: 1.7-3.5, P < 0.001, respectively). Mis-staging was seen to have no negative impact on surgical decision.

Conclusions: MDCT is an accepted tool for renal tumor staging. Tumor mis-staging after MDCT is of little clinical importance. Large tumor size >7 cm and conventional RCC are risk factors for tumor mis-staging.