Clinico-histologic parameters of osteosarcoma patients with late relapse

Primary high-grade intramedullary osteosarcoma of the extremities is a clinically aggressive bone tumour. There is an ongoing effort to further improve efficacy of neo-adjuvant chemotherapy and reduce chemotoxicity by trying to identify osteosarcoma patients who are at risk of treatment failure as well as to identify those who can do with less chemotherapy. In only 5% of patients, first distant metastasis or local relapse occurs 5 years or more after initial treatment for osteosarcoma. Patients and physicians can therefore easily erroneously consider a patient with osteosarcoma cured if he or she is disease-free for more than 5 years following diagnosis and treatment. To investigate if these rare late relapsing patients are characterised by specific clinico-pathological features, we examined clinical and histological variables of late relapse (first local recurrence or metastasis 5 years or more after initial diagnosis) out of a total of 2243 patients, with a special interest in the histological osteosarcoma subtype.