Treatment of osteosarcoma: experience of the Cooperative Osteosarcoma Study Group (COSS).

Using high-dose methotrexate, doxorubicin, and cisplatinum (or BCD) for adjuvant chemotherapy in osteosarcoma of the extremities, we achieved 8-year metastasis-free survival rates of 60-70%. No relapse has been observed after that time. A dose of 12 g/m2 of high-dose methotrexate seems superior to 6 g; doxorubicin was found to be indispensable for efficient therapy and administering ifosfamide in addition seemed to be beneficial. Primary chemotherapy appeared to be safe and to facilitate surgery. The response on chemotherapy provided valuable prognostic information. Salvage of poor responders by alternative postsurgical chemotherapy was unsuccessful. Intraarterial, as opposed to intravenous, use of cisplatinum, in addition to systemic three-drug chemotherapy, did not improve the local tumor response rate. The local failure rate was low (4.7%); it was higher, however, after limb-salvage procedures than after amputation and rotationplasty (11.1% vs. 2.2%, p < 0.05). The outcome after local failure was almost universally fatal. The most intriguing late sequelae of chemotherapy were cardiomyopathy due to doxorubicin and hearing loss due to cisplatinum. Given the limited number of effective drugs, it might be difficult to further improve the cure rate and also to diminish late toxicity. Exploration of the most effective but least toxic mode of drug administration might be one possibility. Another might be reduction of the cumulative doses and therapy duration, while simultaneously increasing the dose rate.