Comparison of the outcome of conventional osteosarcoma at two specialist international orthopaedic oncology centres

Objective: To determine the prognostic value of patient and treatment parameters in osteosarcoma, and whether these are equally important across international boundaries. Design: Retrospective, cross-sectional study of 428 patients diagnosed with around-knee osteosarcoma, between 1990 and 1997 in Birmingham, UK, and Bologna, Italy. Disease-free survival (DFS) and overall survival (OS) assessed by Kaplan-Meier, Fisher's PLSD and Cox proportional hazard regression. Results: Five-year DFS and OS were 56 and 73% at Centre 1, compared to 43 and 60% at Centre 2 (P= 0.0022 and P=0.025, respectively). The most important bad prognostic factors for DFS and OS respectively were raised alkaline phosphatase at diagnosis (P=0.002 and P=0.003), tumour necrosis 150 cm ³ at diagnosis (P=0.04 and P=0.006). The most significant combination of bad prognostic factors was alkaline phosphatase and tumour necrosis. A total of 73% of patients at Centre 1 had greater than 90% necrosis of the tumour following neoadjuvant chemotherapy compared with 29% at Centre 2. Conclusions: Tumour-based prognostic factors have similar significance across international boundaries. Chemotherapy effectiveness appears to be a major factor in explaining the survival difference between the two centres.