Comparison of radiographic and pathologic sizes of renal tumors

We investigated the difference between tumor sizes measured via preoperative computed tomography (CT) images and in surgical specimens during pathologic examinations in a contemporary cohort of patients who received extirpative surgery for renal tumors. We reviewed records of 467 patients who received radical or partial nephrectomy for renal lesions suspicious for malignancy. For our study, only patients who underwent preoperative CT within 4 weeks of surgery were included. In all patients, radiographic tumor size, defined as the largest diameter of tumor measured via CT images, and pathologic tumor size, the largest diameter of tumor measured in surgical specimen, were compared and analyzed by various factors. Among total subjects, mean radiographic and pathologic tumor size were 4.56 +/- A 2.99 and 4.49 +/- A 3.23 cm, respectively (P = 0.399). When subjects were categorized according to radiographic tumor size (1-cm range), statistically significant difference (average of 2 mm) between radiographic and pathologic tumor size was observed only in the 4 to < 5 cm range (P = 0.046). Among those with clear cell renal cell carcinoma, mean radiographic tumor size was significantly larger than pathologic size, but by only 1.4 mm (P = 0.012). Factors such as age, gender, body mass index, tumor stage, tumor grade, and tumor location were observed to have no significant impact on differences observed between radiographic and pathologic tumor size. Although actual size of renal mass can be generally overestimated by CT images, difference may be minimal and clinically insignificant in most cases.