Evaluation of clinical outcomes of antiangiogenic-targeted therapy in patients with pulmonary metastatic renal cell carcinoma using non-contrast-enhanced computed tomography.

RATIONALE AND OBJECTIVES: The objective of this study was to assess whether changes to radiographic parameters before and after treatment with antiangiogenic drugs would improve performance in predicting tumor response with non-contrast-enhanced computed tomography (NCECT) compared to Response Evaluation Criteria in Solid Tumors (RECIST).

MATERIAL AND METHODS: The exploration sample group and the validation sample group consisted of 58 and 25 patients, respectively, who had pulmonary metastatic renal cell carcinoma and were receiving antiangiogenic drugs. All patients underwent NCECT scans at baseline and at first evaluation (after two cycles of treatment) with the same scan protocol. Tumor diameter, attenuation value, entropy, and uniformity of the exploration sample group were examined by receiver operating characteristic (ROC) analysis and stepwise discriminant analysis. The threshold value derived from ROC analysis and discriminant function of the exploration sample group were also used for the validation sample group and were compared to RECIST using Kaplan-Meier survival curves.

RESULTS: According to the model obtained from the exploration group, Kaplan-Meier curves for patients without disease progression were significantly different for the discriminant analysis of the validation sample group (P = .04) and better than individually using RECIST (P = .08), percentage change for attenuation value (P = .49), entropy (P = .47, .89, .72, .73, and .58), and uniformity (P = .53, .72, .51, .39, and .16; without filtration, at scale values of 1.0, 1.5, 2.0, and 2.5, respectively).

CONCLUSIONS: Combined with changes to imaging parameters, including size, attenuation value, and uniformity between pre- and post-treatment, discrimination analysis can help predict biologic response to antiangiogenic drugs and provide a more accurate response assessment than RECIST criteria.