Computer tomography overestimates the actual tumor size of renal cell carcinoma

Abstract

Objective: To evaluate the accuracy ofcomputer tomography (CT) of the kidneyin predicting pathological tumor size ofrenal cell carcinomas (RCC) in patientsreceiving partial nephrectomy (PN) orradical nephrectomy (RN).Patients and Methods: This is a retro-spective review on all PN and RN per-formed for RCC from 2001 to 2014. Themaximum diameter of the tumor on CTscan and that of the surgical specimenwere compared. Nephrectomies done forsynchronous tumours were excluded.Results: 290 patients had preoperativeCT, of which 173 had RN and 117 hadPN. 83% were T1 or T2 tumors, 16% wereT3 tumors and 1% were T4 tumors. Inthis cohort, the mean diameter on CT(5.95 cm) was significantly larger than thaton pathology (5.64 cm) by 0.31 cm(p = 0.000) in paired Student’s t-test. Sub-group analysis of pT1a tumors (N = 127)showed the mean CT diameter (2.84 cm)was larger than the pathological diameter(2.48 cm) by 0.35 cm (p = 0.000). ThepT1b tumors (N = 66) also had a largerdiameter on CT (5.92 cm) than on pathol-ogy (5.24 cm) by 0.70 cm (p = 0.000). Nostatistically significant discrepancy wasobserved for tumours staged T2 or above.Conclusion: CT overestimates the patho-logical tumour size in clinical T1 RCC.Size of RCC on CT should be interpretedcautiously.