The present invention relates to the induction of PPAR&gamma in giant cell tumours that occur in bone and soft tissue, or in chondrosarcoma. Specifically provided is the use of a non-steroidal anti-inflammatory agent selected from the group consisting of zaltoprofen, diclofenac, indomethacin, oxaprozin, acetaminophen, and ketoprofen, in the manufacture of a pharmaceutical composition, for prevention or treatment of giant cell tumors occurring in bone and soft tissue or chondrosarcoma.