Chondrosarcoma and liposarcoma consists of different subtypes with a wide range of patient survival. Current treatment options consist of wide surgical resection, however for patients with a local recurrence or metastatic disease the outcome is poor. New treatment options being evaluated and mouse models show in vivo that mammilian target of rapamycin (mTOR) inhibition can prevent tumour growth. mTOR is an kinase that is present in two complexes and thereby activates multiple pathways. Aberrant mTOR signalling is known to be involved in cancer cell survival. Several clinical studies for patients with bone or soft tissue sarcoma treated with mTOR inhibitors have been conducted and they show promising results. From these studies the investigators can conclude that the combination of an mTOR inhibitor with cyclophosphamide shows promising results in chondrosarcoma. With the lack of other treatment options for unresectable and metastatic chondrosarcoma or myxoid liposarcoma the Eurosarc consortium (www.eurosarc.eu) decided to treat these patients in a standardised way according to a common protocol with the combination of sirolimus and cyclophosphamide using the growth modulation index for evaluation in the current clinical study protocol.