Prognostic value of CT-measured baseline tumor volume in nivolumab-treated metastatic renal cell carcinoma

Objective: To evaluate the association between baseline metastatic tumor volume measured on computed tomography (CT) and survival outcomes in patients with metastatic renal cell carcinoma (mRCC) receiving nivolumab as second line or later line therapy. Materials and Methods: We retrospectively analyzed 43 patients with mRCC treated with nivolumab between August 2013 and March 2022. Baseline metastatic tumor volume was measured on CT scans obtained within 30 days before treatment initiation. The cohort median (117 cm 3 ) was used as an exploratory, data derived cut-off to define low- and high-volume groups. Progression free survival (PFS) and overall survival (OS) were evaluated using Kaplan–Meier analysis and Cox proportional hazards models. Results: Median PFS and OS were 26.97 and 28.11 months, respectively. Median PFS was 40.62 months in the low-volume group and 9.74 months in the high-volume group (p=0.012), while median OS was 46.9 and 12.89 months, respectively (p=0.006). High tumor volume and multiple metastatic sites were associated with poorer survival outcomes. Baseline imbalances in IMDC risk classification and nivolumab treatment line were observed between groups. Conclusion: Higher baseline metastatic tumor volume was associated with poorer survival outcomes in patients with mRCC treated with nivolumab. CT-based tumor volumetry may provide complementary prognostic information; however, these exploratory findings require validation in larger, prospective cohorts.