Chondrosarcoma in Norway 1990-2013: Risk stratification without histology

Abstract

We developed a risk stratification model for Chondrosarcoma (CS) of bone. This is not reliant on histological assessment (grade), which has been the primary tool for risk assessment for 50 years. We found 311 patients with CS in the Cancer Registry of Norway from 1990-2013 and quality controlled all data. The incidence of CS was 2.85 per million per year overall, with an increase in the central subtype. Each subtype has a unique pattern of relapse, allowing tailoring of follow-up regimes. For the central subtype, a soft tissue component was associated with an increased risk of relapse and death. Skeletal location(extremity/axial) and the size of the soft tissue component are also important for prognosis. For tumours in the axial skeleton combined with a soft tissue component ≥1cm(39 patients), the rate of metastasis was 33%- “Oslo high risk”. The other 103 patients had 2% rate of metastasis- “Oslo low risk”. Half of locally recurrent central CS were discovered due to symptoms, the rest by routine imaging. Those with aggressive disease at primary diagnosis also had aggressive disease at recurrence. Oslo risk at primary diagnosis also appeared to predict risk at recurrence.