There is currently no standard follow up protocol for patients who have been diagnosed with and treated for high-grade osteosarcoma. We therefore investigated the possibility of creating a risk based follow-up protocol for patients with primary osteosarcomas.

313 patients diagnosed with primary osteosarcomas were studied. The identified risk factors for local recurrence included poor necrosis, inadequate margins and high risk tumour site in the bone. The risk factors for metastases were poor necrosis, inadequate margins, extra-compartmental stage and tumour size ≥5cm.

The risk of local recurrence and/or metastases within three years of diagnosis increases as the number of risk factors increase. Patients were grouped according to their number of risk factors. The cumulative risk of metastases for patients with 0, 1, 2, 3 and 4 risk factors is 0%, 12%, 21%, 54% and 60% respectively (p=<0.0001). Risk of local recurrence for patients with 0, 1, 2 and 3 risk factors is 5%, 14%, 25% and 20% respectively (p=0.0025).

Our investigation shows that by grouping patients together according to their number of identified risk factors, it is possible to identify groups of patients that are most at risk. This information can be used to design an evidence based follow up protocol which would have important implications for clinical practice.