Skeletal complications and survival in renal cancer patients with bone metastases

Skeletal metastases occur in around one third of patients with advanced or metastatic renal cell carcinoma (RCC). Skeletal involvement is commonly an aggressive, lytic process which causes substantial morbidity through skeletal complications and occurrence of skeletal related events (SREs). However, compared with bone metastases in breast and prostate cancer, there is a paucity of data relating to the demographics of bone metastases in RCC and their sequelae in terms of SREs and survival. The study population included all patients (N=803) with advanced or metastatic RCC treated in a tertiary centre serving a regional population of 2.6 million between 1998 and 2007. Demographic and survival data and information relating to metastatic disease were extracted from electronic records. Thirty-two percent (N=254) of the study population presented with (N=131) or later developed (N=123) bone metastases and 83% of these (N=210) also developed metastases elsewhere. The mean number of SREs experienced by the bone metastatic patients over the course of their disease was 2.4 and only 37 patients experienced no SRE. A high proportion of patients (80%) received radiotherapy for bone pain and there was a surprising and strikingly high incidence of spinal cord/nerve root compression, which was experienced by 28% patients. Although bisphosphonate use increased following the availability of zoledronic acid in 2004, approximately 50% patients with bone metastases did not receive bisphosphonate treatment. The skeletal morbidity rate (number of SREs per patient years at risk) was 1.0 and 1.4 for patients who received or did not receive bisphosphonates, respectively. The median survival following diagnosis of RCC was similar in patients who developed bone metastases (20.4 months) and those who did not (20.9 months). Median survival from diagnosis of metastases was 13.3 months for those who never developed bone metastases, 10.6 months for those who presented with them, 19.6 months for those who developed them later and 22.6 months for patients who had bone only metastases. This is the largest study to date focusing specifically on skeletal complications in RCC. A striking finding was the high incidence of spinal cord/nerve root compression and more research into this area is needed. Clearer, internationally accepted guidelines are recommended for the management of this patient group.