Fall 2012 - 08.pdf 662 | Pre-operative Imaging May Overestimate the Kidney Tumor Size Hamidreza Nasseh, Siavash Falahatkar, Atefeh Ghanbari, Hossein Bagheri Chenari 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-opera- 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 pathol- ogy specimen was 6.2 ± 1.1 cm. Mean tumor size estimated by pre-operative CT scan and ultrasonog- raphy was 7.34 ± 1.83 cm and 7.4 ± 1.96 cm, respectively (P = .001). Tumor stage did not affect this 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 prospec- tive comparison is suggested. Keywords: Corresponding Author: Hamidreza Nasseh, MD Urology Research Center, Razi Hospital, Rasht, Guilan, Iran Tel/Fax: +98 131 552 5259 E-mail: Nasseh_hamid@ yahoo.com Received May 2011 Accepted September 2011 Urology Research Center, Razi Hospital, Guilan Uni- versity of Medical Sciences, Guilan, Iran UROLOGICAL ONCOLOGY Urological Oncology 663Vol. 9 | No. 4 | Fall 2012 |U R O LO G Y J O U R N A L INTRODUCTION T umor size is an important clinical and pathologic feature for evaluating patients with renal cell car- cinoma (RCC). The pT1a, pT1b, and pT2 primary depending just on the tumor size.(1) Tumor size has sub- stantial clinical implications for patients with a renal mass. the prediction of prognosis, and helps in choosing the best treatment modality, including observation, partial nephrec- tomy, or radical nephrectomy.(2) Furthermore, size of the kidney tumor and its location enjoin the surgical approach, such as nephron-sparing surgery (NSS) for smaller lesions, incision for large upper pole lesions, or a transperitoneal approach for bilateral lesions operated on in one session. Recently, tumor size is mostly represented by pathologic size, which is routinely estimated during pathologic sec- tioning.(2,3) Studies reporting the appropriate size cutoff for the use of NSS have used the pathologic size of the renal tumor. On the other hand, NSS is chosen as a treatment mo- dality based on the radiologic size. Novick concluded that the tumor size has gradually gained acceptance for elective NSS.(4,5) In addition, the pathologic size is not always avail- able in patients who are treated by percutaneous or laparo- scopic ablation procedures(6,7) or laparoscopic nephrectomy with subsequent tumor morcellation. Several previous observations suggest that there is an over- estimation of pathologic size of renal tumors compared with radiographic size, which may have implications for plan- ning NSS.(8-11) Radiographic overestimation may diminish the number of patients who would otherwise be candidates for a nephron-sparing approach.(10) computed tomography (CT) depicts more renal masses than - (12) Due to paucity of studies comparing pathologic kidney tu- mor size with both ultrasonography and CT scan size, we performed this study to compare the radiographic size of the tumor by CT scanning and ultrasonography prior to the surgery with the pathologic size of the tumor after the sur- gery. MATERIALS AND METHODS The medical records of patients treated by open or laparo- scopic radical nephrectomy for localized RCC from March 2003 to March 2009 were retrospectively reviewed. Patients with positive surgical margin, multiple tumors, im- aging performed more than two months before the surgery, benign or cystic lesions, partial nephrectomy, and incom- Finally, 40 patients met the inclusion criteria. Patients’ de- mographic characteristics, including age, gender, histology, type of procedure, and cancer stage, were collected from the records. The radiologic and pathologic reports were also reviewed, and tumors were staged according to the 2002 TNM staging system.(1) All the patients had undergone a helical intravenous con- trast-enhanced abdominal CT scan and ultrasonography by solitary renal neoplasm. The largest of diameter measure- size. Tumor stage, size, and histologic subtype were determined from the pathology reports. The pathologic tumor size was The mean values of CT scan, ultrasonography, and patho- Kidney Tumor Size | Nasseh et al Table 1. Demographic characteristics of the patients. Parameters Patients Mean age (range), y 64.12 (42 to 79) Gender, n (%) Male 25 (62.5%) Female 15 (37.5%) Type of procedure, n (%) Open radical nephrectomy 33 (82.5%) Laparoscopic radical nephrectomy 7 (17.5%) Histology, n (%) Clear cell 31 (77.5%) Non clear cell 9 (22.5%) Staging, n (%) T1 25 (62.5%) > T1 15 (37.5%) 664 | logic sizes, and their difference were calculated. Paired Student’s t test was used to compare the mean values. The correlation between radiological and pathological sizes was statistical testing. Statistical analysis was performed using SPSS software (the Statistical Package for the Social Sci- ences, Version 18.0, SPSS Inc, Chicago, Illinois, USA). RESULTS Demographic characteristics of patients are shown in Table from the study. The average interval from pre-operative CT scan and ultrasonography to surgery was 29.9 days (range, 1 to 60 days). The mean pathologic, CT scan, and ultrasonography sizes are shown in Table 2. The mean radiological tumor sizes for - 1.14 cm and 1.2 cm larger on the CT scan and ultrasonog- raphy assessment versus the pathologic measurement (P = .001 and P = .001, respectively). Mean ultrasonographic and CT scan size difference (0.06 cm) was not statistically P = .39). tumor size by CT scan and ultrasonography for both T1 and > T1 stages (Table 2), but mean difference was higher in T1 stage. The mean change in size for T1 tumors was 1.61 cm larger on the CT scan assessment versus the pathologic measurement while this difference was 0.35 cm for T2 tu- mors. The mean size of T1 tumors was 1.63 cm larger on the ultrasonography assessment versus the pathologic meas- urement, while this difference was 0.52 cm for T2 tumors. Scatter plot of radiological sizes (ultrasonography and CT scan sizes) and pathological size are shown in Figures 1 and 2, respectively. According to Figures, radiological sizes correlated with pathological size. DISCUSSION - lationship between the radiographic and pathologic tumor Figure 1. Regression line between pathology and ultrasonogra- phy sizes (cm). (r = 0.80, P < .001) (R2 = 0.644, P < .001) Figure 2. Regression line between pathology and computed tomography scan sizes (cm). (r = 0.94, P < .001) (R2 = 0.89, P < .001) Table 2. Mean tumor size estimated by ultrasonography, CT scan, and pathology.* Ultrasonography CT scan Pathology P (Ultrasonography and Pathology) P (CT scan and Pathology) T1 5.6 ± 0.53 5. 58 ± 0.65 3.97 ± 0.31 .001 .001 > T1 10.44 ± 0.66 10.26 ± 0.63 9.92 ± 0.65 .007 .002 overall 7.4 ± 1.96 7.34 ± 1.83 6.2 ± 1.1 .001 .001 *CT indicates computed tomography. Urological Oncology 665Vol. 9 | No. 4 | Fall 2012 |U R O LO G Y J O U R N A L Kidney Tumor Size | Nasseh et al sizes.(3,8,9,13,14) Herr prospectively reviewed 50 patients who had undergone partial nephrectomy and found that the clini- cal tumor size (pre-operative CT) was 0.63 cm (range, 2.2 to 0.4 cm) larger than the pathologic size. Moreover, he re- - after ligation or occlusion of the renal artery. The decrease whole kidney shrank. This helps the surgeon resect larger tumors completely within a safe margin, regardless of the size of the kidney as a whole.(8) In a follow-up study, Herr and coworkers found that the greatest difference was seen in clear cell carcinoma and tu- mors > 3 cm. They concluded that because the shrinkage was consistent, tumors with a radiographic diameter slight- ly larger than 4 cm could still meet the 4-cm pathologic size criterion after partial nephrectomy.(9) Irani and coworkers retrospectively studied 100 patients with renal tumors who had undergone radical nephrectomy. They reported that the average pathologic tumor size was versus 70 mm). They also found that the smaller the tumor, the more the clinical size overestimated the pathologic size. overestimated the tumor size more in smaller tumors, and of the tumor.(15) tumors smaller than 5 cm.(10) Similarly, Choi and associ- ates stated that pre-operative CT imaging may overestimate tumor size in RCCs of smaller than 6 cm.(14) In the present study, we compared both ultrasonography and CT scan sizes with pathologic tumor size in patients previous reports which found that pre-operative CT may overestimate the pathologic size. While radiological sizes correlated with pathological size, renal tumors were on av- erage 1.14 cm and 1.2 cm smaller after nephrectomy than what the CT scan and ultrasonography estimated before the surgery. Changes in radiographic and pathologic tumor sizes were more pronounced in patients with smaller tumors (stage T1), which are the best candidates for NSS. which suggests that CT imaging estimates renal tumor size in a manner that is compatible with ultrasonography. In our study, the CT scan and ultrasonography estimations of tumors were similar in all sizes, which is compatible with results that Jamis-Dow and colleagues found in small renal masses. They understood, however, that neither modality is perfect.(12) tumor shows larger view of the tumor, which may result in selecting an inappropriate treatment and a falsely worsened overall prognostic prediction. - sign is retrospective; CT scans have been performed else- where; the radiologic and pathologic measurements were not done in the same geometric dimensions; and the CT scan apparatus and technicians were not the same for all the patients. CONCLUSION renal tumor sizes comparing CT scan and ultrasonography with pathology. This point must be considered in clinical staging and treatment selection. However, multicenter pro- spective comparison is suggested. CONFLICT OF INTEREST None declared. REFERENCES 1. Greene FL, Page DL, Flemming ID, et al. AJCC Cancer Staging Manual. Vol 1. 6 ed. New York: Springer-Verlag; 2002. 2. Kurta JM, Thompson RH, Kundu S, et al. Contemporary im- aging of patients with a renal mass: does size on computed tomography equal pathological size? BJU Int. 2009;103:24- 7. 3. Yaycioglu O, Rutman MP, Balasubramaniam M, Peters KM, Gonzalez JA. Clinical and pathologic tumor size in renal cell carcinoma; difference, correlation, and analysis of the influencing factors. Urology. 2002;60:33-8. 666 | 4. Novick AC. Laparoscopic and partial nephrectomy. Clin Cancer Res. 2004;10:6322S-7S. 5. Uzzo RG, Novick AC. Nephron sparing surgery for renal tumors: indications, techniques and outcomes. J Urol. 2001;166:6-18. 6. Berger A, Kamoi K, Gill IS, Aron M. Cryoablation for renal tumors: current status. Curr Opin Urol. 2009;19:138-42. 7. Krehbiel K, Ahmad A, Leyendecker J, Zagoria R. Thermal ablation: update and technique at a high-volume institu- tion. Abdom Imaging. 2008;33:695-706. 8. Herr HW. Radiographic vs surgical size of renal tumours after partial nephrectomy. BJU Int. 2000;85:19-21. 9. Herr HW, Lee CT, Sharma S, Hilton S. Radiographic versus pathologic size of renal tumors: implications for partial nephrectomy. Urology. 2001;58:157-60. 10. Schlomer B, Figenshau RS, Yan Y, Bhayani SB. How does the radiographic size of a renal mass compare with the patho- logic size? Urology. 2006;68:292-5. 11. Kanofsky JA, Phillips CK, Stifelman MD, Taneja SS. Impact of discordant radiologic and pathologic tumor size on renal cancer staging. Urology. 2006;68:728-31. 12. Jamis-Dow CA, Choyke PL, Jennings SB, Linehan WM, Thakore KN, Walther MM. Small (< or = 3-cm) renal masses: detection with CT versus US and pathologic correlation. Radiology. 1996;198:785-8. 13. Ates F, Akyol I, Sildiroglu O, et al. Preoperative imaging in renal masses: does size on computed tomography corre- late with actual tumor size? Int Urol Nephrol. 2010;42:861- 6. 14. Choi JY, Kim BS, Kim TH, Yoo ES, Kwon TG. Correlation be- tween Radiologic and Pathologic Tumor Size in Localized Renal Cell Carcinoma. Korean J Urol. 2010;51:161-4. 15. Irani J, Humbert M, Lecocq B, Pires C, Lefebvre O, Dore B. Renal tumor size: comparison between computed tomog- raphy and surgical measurements. Eur Urol. 2001;39:300-3. Urological Oncology