ADDITION OF PRIMARY METASTATIC SITE IN BONE, BRAIN, AND LIVER TO IMDC CRITERIA IN PATIENTS WITH METASTATIC RENAL CELL CARCINOMA. A VALIDATION STUDY.

Abstract Background IMDC criteria have been largely adopted in clinical practice. In a recent retrospective study, we assessed that the addition of the first site of metastatic disease to brain bone and liver improves prognostic stratification of patients with metastatic renal cell carcinoma (mRCC). Aim Here we performed an external validation in patients with mRCC. Our aim was to evaluate if the addition of a new independent variable could improve IMDC prognosis prediction and reduce heterogeneity within risk category. Methods We selected all 1073 patients treated at a single institution for mRCC and included in the IGReCC database. All patients included received at least one line of targeted therapy or immune-checkpoint inhibitors. Univariate and multivariate analyses (Cox regression model) were performed. Bootstrap of the final model was also carried out for internal validation. IMDC modified classification was defined by the addition of the 7th variable and we defined good IMDC modified as O risk, intermediate 1-2, poor >3 or more criteria. Results The presence of brain, bone and/or liver as the first site of metastatic disease plus the other variables included in the IMDC score resulted as statistically significant variables associated with OS after univariate, multivariate and bootstrap validation. Finally, 122 (15%) of patients modified their initial risk category. Median OS in poor, intermediate and favorable was 10, 26 and 52 months, respectively (p Conclusion The addition of brain, bone and/or liver metastases as another variable to the other IMDC variables improves the prognostic predictive power of the model.