[Clinical and pathological analysis of renal cell carcinoma bone metastasis]

To analyze the clinical and pathological characteristics of renal cell carcinoma bone metastasis (RCC-BM) patients.

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.

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 endothelial 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.

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.