Osteosarcoma: the COSS experience.

COSS, the interdisciplinary Cooperative German-Austrian-Swiss Osteosarcoma Study Group, was founded in 1977 and has since registered some 3,500 bone sarcoma patients from over 200 institutions. For the purpose of the Pediatric and Adolescent Osteosarcoma Conference in Houston, March 2008, the outcomes of 2,464 consecutive patients with high-grade central osteosarcoma, who had been diagnosed between 1980 and 2005 and had been treated on neoadjuvant COSS protocols, were reviewed. Intended treatment had included surgery and multidrug chemotherapy, with high-dose methotrexate, doxorubicin, cisplatin, and ifosfamide being used in most protocols. After a median follow-up of 7.31 years for 1,654 survivors, 5- and 10-year survival estimates were 0.748/0.695 for 2,017 patients with localized extremity tumors and 0.369/0.317 for 444 patients with axial tumors or/and primary metastases, respectively. Tumor response to preoperative chemotherapy was of independent prognostic significance. Over the years, there was a major shift from amputation towards limb-salvage. This development was least evident for patients below the age of 10. While survival expectancies improved from the first to the second half of the recruitment period, no further improvement was evident within the latter period. In the manuscript, the results described above are discussed based on the findings of the previous analyses of our group.