Association of primary tumor radiomic phenotypes and outcomes in patients (pts) with metastatic renal cell clear cell carcinoma (mRCC) treated with cytoreductive nephrectomy (CN).

622 Background: Despite the advances in systemic therapy for mRCC, CN may benefit a subset of pts. We investigated the correlation of clinical outcomes with primary tumor radiomics and radiology measurements of primary and metastatic lesions in mRCC pts treated with CN. Methods: We searched our institutional database for mRCC pts referred for CN from July 2011 to October 2019. Key eligibility criteria included clear cell histology, measurable metastatic disease, and OS >60 days from CN, to avoid surgery-related deaths. Demographics and IMDC risk strata were collected from medical charts. Volumetry and radiomic features (first and second order) were assessed in the arterial phase abdominal computerized tomography (CT) of the primary lesion. Metastatic disease foci were segmented from venous phase CT and measured. Bone disease and <1cm visceral metastases were disregarded for 3-axial measurement. After dimensionality reduction of the radiomic features with Uniform Manifold Approximation and Projection, an unsupervised Gaussian Mixture Model (GMM) clustering was performed. Characteristics of different clusters were compared with Mann-Whitney U test and univariate Cox regression estimated the effect on outcomes. Results: From 54 mRCC pts treated with CN, 39 were included. Median age was 60 years-old. Most patients were male (74%) and intermediate-risk by IMDC (64%). Sites of metastasis included lung (44%), bone (38%), and adrenal (21%). GMM identified 4 distinct clusters from radiomic features, which were grouped according to median OS relative to all pts (2.8 years): Group A (below mOS) and Group B (above mOS). The table shows the association of different factors with OS. Group B had longer median OS (3.4 vs. 1.8 years, p=0.009), progression-free survival (16.8 vs. 9.8 months, p=0.024), systemic treatment-free survival (9.5 vs. 3.8 months, p=0.028), and survival during first-line tyrosine kinase inhibitor (2.2 vs. 0.9 years, p=0.016). Group men had a lower primary-to-whole-body burden ratio compared to Group A (median 0.83 vs. 0.99, p<0.01). Only IMDC risk criteria (HR 1.97, p<0.01) and radiomic group B (HR 0.35, p=0.01) correlated with OS in univariate Cox analysis. Conclusions: Our study suggests that radiomics of the primary lesion may predict OS in mRCC pts after CN, despite limited by its retrospective nature and small sample size. Further validation in larger datasets is warranted. Univariate Cox proportional hazards of prognostic factors on OS. [Table: see text]