Abstract
Chondrosarcoma (CS) is a rare tumour type and the most common primary malignant bone cancer in adults. The prognosis, currently based on tumour grade, imaging and anatomical location, is not reliable, and more objective biomarkers are required. We aimed to determine whether the level of circulating tumour DNA (ctDNA) in the blood of CS patients could be used to predict outcome. In this multi‐institutional study, we recruited 145 patients with cartilaginous tumours, of which 41 were excluded. ctDNA levels were assessed in 83 of the remaining 104 patients, whose tumours harboured a hotspot mutation in IDH1/2 or GNAS. ctDNA was detected pre‐operatively in 31/83 (37%) and in 12/31 (39%) patients postoperatively. We found that detection of ctDNA was more accurate than pathology for identification of high‐grade tumours and was associated with a poor prognosis; ctDNA was never associated with CS grade 1/atypical cartilaginous tumours (ACT) in the long bones, in neoplasms sited in the small bones of the hands and feet or in tumours measuring less than 80 mm. Although the results are promising, they are based on a small number of patients, and therefore, introduction of this blood test into clinical practice as a complementary assay to current standard‐of‐care protocols would allow the assay to be assessed more stringently and developed for a more personalised approach for the treatment of patients with CS.
Highlights
Central conventional chondrosarcoma (CS) and dedifferentiated chondrosarcoma (DDCS)represent the most common primary bone tumours in adults
We found that detection of circulating tumour DNA (ctDNA) was more accurate than pathology for identification of high-grade tumours and was associated with a poor prognosis; ctDNA was never associated with CS grade 1/atypical cartilaginous tumours (ACT), which are neoplasms sited in the small bones of the hands and feet or in tumours measuring less than 80 mm
In 2011, we reported that approximately 60% of central conventional and dedifferentiated CS harbour either an IDH1 or an IDH2 hotspot mutation[12], [13]
Summary
Central conventional chondrosarcoma (CS) and dedifferentiated chondrosarcoma (DDCS)represent the most common primary bone tumours in adults. Clinical management and prognosis for this disease is largely determined by assessment of tumour grade and staging[1], [2] in the context of the anatomical site, and imaging of the primary tumour[2]. Well-differentiated central cartilaginous tumours include enchondroma, atypical cartilaginous tumour (ACT) and CS Grade (G) 1. ACT and CS G1 account for approximately 50% of central cartilaginous tumours (the incidence of enchondromas is unknown); they exhibit similar histological features and are distinguished on the basis of anatomical site, which determines clinical outcome and management[2]. Well differentiated cartilaginous tumours occurring in the small tubular bones of the hands and feet and long bones have an excellent clinical outcome following curettage and are referred to as ACT[2]. A risk of transformation to a higher grade comes with incomplete excision[6]
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