Characterizing sites of metastatic involvement in metastatic clear-cell, papillary, and chromophobe renal cell carcinoma.

Abstract

5071 Background: There exists considerable biological and clinical variability between histologic variants of metastatic renal-cell carcinoma (mRCC). Data reporting on sites of metastatic involvement in less common histologies of mRCC are sparse. We sought to characterize the frequency of metastatic site involvement across the three most common histologies of mRCC: clear-cell (ccRCC), papillary (pRCC), and chromophobe (chrRCC). Methods: Using the International mRCC Database Consortium (IMDC) database, patients with mRCC starting systemic therapy between 2002-2019 were identified and sites of metastases at the time of systemic therapy initiation were documented. Patients with multiple sites of metastatic involvement were included in analyses of all groups to which they had metastases. The primary outcomes were prevalence of metastatic site involvement and overall survival (OS). Patients with mixed histology were excluded. Results: 10,105 patients were eligible for analysis. Median age at diagnosis was 60, 72% were male and 79% underwent nephrectomy. 92%, 7% and 2% of patients had ccRCC, pRCC, and chrRCC, respectively. Frequency of metastatic site involvement across the histologic subtypes is shown in Table. Lung, adrenal, brain and pancreatic metastases were more frequent in ccRCC, lymph node involvement was most frequent in pRCC, and liver metastases were most frequent in chrRCC. Median OS for ccRCC varied by site of metastatic involvement, ranging between 16 months (brain/pleura) and 50 months (pancreas). OS by site of metastatic involvement was compared between histologies for the four most common sites of metastases (lung, lymph nodes, bone, liver). As compared to patients with ccRCC, patients with pRCC had lower OS regardless of site of metastasis (p < 0.05). Power was limited and thus differences in OS between ccRCC and chrRCC were not detectable. Conclusions: Sites of metastatic involvement differ based on histology in mRCC. These data highlight the clinical and biologic variability between histologic subtypes of mRCC and constitute the largest cohorts of patients with metastatic pRCC and chrRCC to report on sites of metastases. Sites of Metastatic Involvement by Histology. [Table: see text]