Bone metastases in soft tissue sarcoma: a survey of natural history, prognostic value and treatment options.

We surveyed the natural history of bone metastases in patients affected by soft tissue sarcoma (STS).This multicenter retrospective observational study included 135 patients. Histological subtype, characteristics of bone metastases, treatment, skeletal related events (SREs) and disease outcome were recorded.The most represented histological subtypes were leiomyosarcoma (27%) angiosarcoma (13%) and undifferentiated sarcoma (8%). Axial skeleton was the most common site for bone involvement (70%). In 27% of cases, bone metastases were present at the time of diagnosis. Fifty-four (40%) patients developed SREs and the median time to first SRE was 4 months (range 1-9). The most common SRE was the need for radiotherapy (28%) followed by pathological fracture (22%). Median survival after bone progression was 6 months (range 1-14). SREs were associated with decreased overall survival (OS) (P = 0.04). A subgroup analysis revealed that bisphosphonates significantly prolonged median time to first SRE (5 versus 2 months; P = 0.002) while they did not determine an improvement in OS, although a favourable trend was identified (median: 7 versus 5 months; P = 0.105).This study illustrates the burden of bone disease from STS and supports the use of bisphosphonates in this setting