Bone is the second most common site of metastasis of advanced renal cell carcinoma (RCC) [1,2]. Skeletal involvement is found in 20% to 39% of RCC patients. Skeletal-related events (SREs), which include pathological fractures, radiotherapy, surgery, nerve compression, or hypercalcaemia, affect 74-85% RCC patients with bone metastasis (BM) and severely deteriorate RCC patients’ quality of life [3]. BM also serves as a predictive factor for poor clinical outcome of RCC [1,4,5]. The OS of RCC with BM is reported to be only 13.2-19.5 months, which is far below the OS of 20.2-38.5 months of RCC without BM [1,6].

In clinic, there is a small group of patients with metastatic RCC whose tumor show an exquisite bone tropism and develop exclusive skeletal metastases. A few studies discordantly report that RCC patients with bone-only metastasis have better prognosis than those with extraosseous metastasis ± BM [7,8]. The OS of RCC patients with bone-only metastasis was reported to be 46.4 months, which was statistically far longer than the OS of 17.6 months of those with concomitant visceral and lymph nodal metastases [7]. Although nowadays tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs) have become the cornerstones of systemic therapy for advanced RCC, their role in RCC with bone metastasis is elusive. 2022 ASCO guideline of management of metastatic clear cell RCC made no recommendation regarding optimal systemic treatment for metastatic RCC with BM [9]. So the management of RCC with bone-only metastasis is a debating issue [9,10].

To investigate the biological behaviour and natural history of RCC with bone-only metastasis and provide more clues for clinicians, we conducted this retrospective study.