Choi response criteria for prediction of survival in patients with metastatic renal cell carcinoma treated with anti-angiogenic therapies.

OBJECTIVE: Anti-angiogenic drugs cause a reduction in tumour density (Choi criteria) first and then in size [Response Evaluation Criteria In Solid Tumours (RECIST)]. The prognostic significance of changes in tumour density in metastatic renal cell carcinoma (mRCC) is unknown and was assessed in this study.

METHODS: The prognostic significance of partial response (PR) as opposed to non-response [stable disease (SD) + progressive (PD)] to anti-angiogenic therapy was assessed in patients with mRCC separately for both criteria using the log-rank test and Cox regression models.

RESULTS: Both criteria were applied to 35 patients. The response was identical for all eight patients with PR and most patients with PD (10/12) when using the RECIST and Choi criteria. Adding tumour density information, 14 patients with SD were re-categorised as having PR (7), SD (4), and PD (3). Patients with PR (Choi) were progression free significantly longer [hazard ratio (HR) 0.24; 95 % CI 0.10-0.57; P = 0.001] and had better overall survival (HR 0.36; 95 % CI 0.15-0.89; P = 0.026) compared to patients with SD or PD. The predictive value of PR according to RECIST was not statistically significant.

CONCLUSIONS: In mRCC, the Choi criteria separate prognostic groups better when compared with RECIST. This may allow early discrimination of patients benefiting from continued treatment.