Abstract: Objective： To analyze the clinical and pathological characteristics of renal cell carcinoma bone metastasis (RCC-BM) patients. Methods: Data of RCC-BM patients from July 2003 to November 2017 were retrospectively reviewed.  The patients’ baseline characteristics (age, gender), tumor characteristics ［specific sites of bone metastasis, time to bone metastasis (TTBM), imaging features of bone disease, coexistence of other metastasis］, as well as pathological features (histological classification of primary and bone metastasis, immunohistochemical stain results) were collected. Descriptive analysis and difference analysis were used. Results: A total of 113 RCC-BM patients were enrolled with the gender ratio (male ∶female) of 4 ∶1, mean age of 59.39 years, and all present of osteolysis bone lesions. The common sites of bone metastasis were vertebra (46.0%) and pelvis (38.9%). Other distant metastasis sites coexisted in 28.3%, while 48.18% RCC-BM patients presented with synchronous metastasis (TTBM=0). The median TTBM for metachronous metastasis was 48 months. The majority in this cohort were determined to have primary tumor of clear cell carcinoma. After immunohistochemical examination to 104 RCC-BM patients and sub-group analysis, tendencies of higher positive rates of vascular endothelial growth factor (VEGF) was also found in synchronous group (P=0.097) while tendencies of higher positive rates of carbonic anhydrase (CA)-Ⅸ was found in the same group (P=0.100). The patients with clear cell RCC-BM had a significantly higher positive expression of epithelial growth factor receptor (EGFR, P<0.05) than those with non-clear cell RCC-BM group. Conclusion: More male and younger patients with metastatic lesions in axial skeleton were found in this cohort. Tendencies in the expression of CA-Ⅸ and VEGF in different TTBM sub-group and EGFR in different histology-derived subgroup indicate that they might be associated with risk and prognostic factors and support further target therapies of RCC-BM.

Key words: Renal cell carcinoma, Neoplasm metastasis, Bones, Clinical pathology