Renal tumor size: Comparison between computed tomography and surgical measurements

Objective: We studied the agreement between renal tumor size as assessed on computed tomography (CT) before surgery and that measured during histopath ological examination on the radical nephrectomy specimen. Methods: We retrospectively analyzed the records of 100 consecutive patient s treated with radical nephrectomy for a renal tu mor. The tumor size was d etermined in all patients by the largest diameter shown within the month be fore surgery on contrast-enhanced CT and as measured postoperatively by the pathologist. A possible influence of the clinical and pathological paramet ers was assessed in a multivariate analysis. Results: CT estimate and surgical measurement of tumor size were highly cor related (r = 0.9; p<0.001). Median (range) tumor size was 70.0 mm (13-180) and 60.0 mm (10-180) as measured, respectively, on CT and in the specimen, with a significant difference (p = 0.005). Multiple regression did not reve al any significant influence of tumor side, location, type, nuclear grade a s well as patient gender, body mass index and radiological center (p>0.3 in all cases). The extent of difference between CT and surgical measurements was significantly influenced by the surgical size of the tumor (p = 0.03): the smaller the tumor, the more the CT overestimated the tumor size. If nep hron-sparing surgery had been planned for tumors equal to or less than 40 m m, 24 patients would have been selected following the CT estimate, while 27 patients would have met this criterion on the surgical measurement. Conclusion: Renal tumors were statistically smaller than the estimate from CT, although this was not systematically the case. This should be kept in m ind when issuing recommendations on the optimal cutoff size value under whi ch nephron-sparing surgery is considered equivalent to radical nephrectomy. Copyright (C) 2001 S. Karger AG. Basel.