Comparison of pre-treatment MSKCC and IMDC prognostic risk models in patients with synchronous metastatic renal cell carcinoma treated in the era of targeted therapy.

Purpose: To compare prognostic performance of MSKCC and IMDC risk models in patients with synchronous mRCC.

Methods: Retrospective analysis of pre-therapeutic MSKCC and IMDC prognostic factors and outcomes in patients with synchronous mRCC treated at a single institute in the targeted therapy era was performed. Cytoreductive nephrectomy (CN) was performed in patients with WHO performance 0-1 and limited metastasis.

Results: Of 190 patients, only 2 had favourable risk. Overall, 141 patients received targeted therapy and 97 underwent CN. By MSKCC score, 143 (76.1 %) patients were intermediate risk (median OS 16 months) but only 97 (51.9 %) by IMDC (median OS 23 months). Conversely, 46 of the MSKCC intermediate-risk patients (31.2 %) were IMDC poor risk. Only poor risk by MSKCC and ≥4 IMDC factors had similar poor outcome (median OS 5 months and OS 2 years of 4.1 % and 10.4 %, respectively). Following CN, baseline elevated platelets and neutrophils decreased to normal in 61.5 and 75 %, respectively. This suggests that the primary tumour may influence baseline counts resulting in more IMDC poor risk. In both models, CN status was associated with better OS.

Conclusion: Patients with synchronous mRCC and poor risk by MSKCC or ≥4 IMDC factors have a short survival expectancy, and CN may not be the primary objective in this population. Conversely, with either MSKCC or IMDC intermediate risk the probability to survive 2 years is 38.6-45.7 %, which suggests that a subgroup of patients live long enough to derive a potential benefit of CN.