Tumor burden and site of metastatic disease are well-established prognostic factors in many malignancies, including mRCC. This analysis aims to evaluate the impact of bone metastasis location in the clinical outcome of mRCC patients.

A retrospective analysis using the collaborative cohort of mRCC patients enrolled in the database from LARCG was performed. This consortium includes 45 centers from 9 countries including Uruguay, Brasil, Argentina, Mexico, Peru, Chile, Bolivia, and Spain. Clinico-pathological characteristics, 24-months-survival, overall survival (OS), as well as sites of bone metastatsis were collected. Clinico-pathological characteristics are presented descriptively. Cox regression was utilized to estimate the association of bone metastasis location and clinical outcomes.

From 1990 to 2015, 4060 patients were included in the LARCG dataset. The majority of patients had localized RCC. 530 (14.5%) patients had metastasis at diagnosis. Out of 530, 56 had exclusively bone metastasis. Median follow-up was 20.8 months (0-188). Survival data was available for 55 out of those 56 patients. Thirty-six (64.3%) patients were male. The median age of was 59.5 years (40-85), and 48(90.6%) had symptoms at presentation. Primary nephrectomy was performed in 46 patients (82.1%) and systemic therapy was VEGF-targeted therapy and cytokines in 35 and 1 patients, respectively. Non-vertebral bone metastasis (NVBM) were identified in 33(58.9%) patients and vertebral metastasis (VBM) in 23(41.1%) patients. Median OS for the overall cohort of mRCC patients was 24 months. The 24-months OS was, 87% for patients with NVBM vs. 50% for VBM patients (HR: 2.70, 95% CI: 1.10 – 6.61; p=0.029 – univariate analysis). Sarcomatoid component was associated with vertebral metastatsis (p=0.041).

Although we have analyzed a small number of patients, vertebral bone metastasis appear to be associated with shorter 24-months OS, suggesting that location of bone metastasis may impact the clinical outcome of patients with mRCC.