We evaluated the long-term outcome of patients with an osteosarcoma who had undergone prior manipulative therapy, a popular treatment in Asia, and investigated its effects on several prognostic factors. Of the 134 patients in this study, 70 (52%) patients had manipulative therapy and 64 (48%) did not. The age, location, and size of tumour were not significantly different between the groups. The five-year overall survival rate was 58% and 92% in the groups with and without manipulative therapy (p = 0.004). Both the primary and overall rates of lung metastasis were significantly higher in the manipulative group (primary: 32% vs 3%, p = 0.003; overall lung metastasis rate: 51.4% vs 18.8%, p < 0.001). Patients who had manipulative therapy had higher local recurrence rates in comparison to patients who did not (29% vs 6%, p = 0.011). The prognosis for patients with osteosarcoma who had manipulative therapy was significantly poorer than those who had not. Manipulative therapy was an independent factor for survival.

This form of therapy may serve as a mechanism to accelerate the spread of tumour cells, and therefore must be avoided in order to improve the outcome for patients with an osteosarcoma.