Pre-operative imaging may overestimate the kidney tumor size.

PURPOSE To compare the kidney tumor size on radical nephrectomy pathology specimen with size estimated by computed tomography (CT) scan and ultrasonography. MATERIALS AND METHODS The tumor size on pathology specimen of 40 patients who had undergone radical nephrectomy at our center from March 2003 until March 2009 was compared with pre-operative CT scan and ultrasonography findings. The paired t test was used to compare the means. RESULTS The participants included 40 patients, 25 men and 15 women, with the mean age of 64.12 ± 10.75 years (range, 42 to 79 years). All tumors were renal cell carcinoma. Mean tumor size on pathology specimen was 6.2 ± 1.1 cm. Mean tumor size estimated by pre-operative CT scan and ultrasonography was 7.34 ± 1.83 cm and 7.4 ± 1.96 cm, respectively (P = .001). Tumor stage did not affect this significant difference. There was not any significant difference between tumor size estimated by CT scan or ultrasonography (P = .39). CONCLUSION Computed tomography scan and ultrasonography both may overestimate renal tumor size. This point must be considered in clinical staging and treatment selection. Multicenter prospective comparison is suggested.