Contrast-Enhanced CT Density Predicts Response to Sunitinib Therapy in Metastatic Renal Cell Carcinoma Patients

The first-line therapy in metastatic renal cell carcinoma (mRCC), sunitinib, exhibits an objective response rate of approximately 30%. Therapeutic alternatives such as other tyrosine kinase inhibitors, VEGF inhibitors, or mTOR inhibitors emphasize the clinical need to predict the patient's response to sunitinib therapy before treatment initiation. In this study, we evaluated the prognostic value of pretreatment portal venous phase contrast-enhanced computed tomography (CECT) mean tumor density on overall survival (OS), progression-free survival (PFS), and tumor growth in 63 sunitinib-treated mRCC patients. Higher pretreatment CECT tumor density was associated with longer PFS and OS [hazard ratio (HR) = 0.968, P = .002, and HR = 0.956, P = .001, respectively], and CECT density was inversely correlated with tumor growth (P = .010). Receiver operating characteristic analysis identified two CECT density cut-off values (63.67 HU, sensitivity 0.704, specificity 0.694; and 68.67 HU, sensitivity 0.593, specificity 0.806) which yielded subpopulations with significantly different PFS and OS (P < .001). Pretreatment CECT is therefore a promising noninvasive strategy for response prediction in sunitinib-treated mRCC patients, identifying patients who will derive maximum therapeutic benefit.