(P 156) CHONDROSARCOMA INCIDENCE, SURVIVAL AND MANAGEMENT IN ENGLAND 2013-2022; AN ANALYSIS FROM THE NATIONAL DISEASE REGISTRATION SERVICE

Objective: Chondrosarcoma (CS) is an uncommon primary malignant bone tumour with histologically distinct subtypes, with differing management and outcomes. In England, all cancer diagnoses are registered with the National Disease Registration Service, providing an opportunity for this national population-based study that sought to describe the incidence, management and outcomes of patients registered with CS.

Methods: All patients diagnosed with CS, resident in England between 2013 and 2022, were included. Age-standardised incidence rates per 100,000 person-years (ASR) were calculated for all subtypes. Outcome was assessed by five-year relative survival (RS) and Cox proportional hazards modelling to determine impact of patient characteristics and treatment on outcome, including histological subtype, primary site and grade; age at diagnosis, gender, deprivation and treatment within 12 months of diagnosis.

Results: A total of 1,816 CS patients were included; 1,589 (84%) with conventional CS (CCS), 133 (7%) with dedifferentiated CS (DDCS) and 34 (2%) with mesenchymal CS (MC). Overall ASR was 0.34, ranging from 0.30 in CCS to 0.001 for malignant chondroblastoma.
DDCS patients were older than CCS patients (median age 67 vs 54 years). Primary site varied; extremity was most common overall (58%) but more frequent in DDCS (72%) and CCS (57%) than MC (29%). Pelvic site was more common in DDCS (23%) than CCS (13%).
At total of 1,319 CCS patients (83%), 109 DDCS patients (82%) and 25 MC patients (74%) had surgery. Systemic therapy use was rare in CCS (1.7%); more common in DDCS (22%) and MC (59%). Radiotherapy use was most frequent in MC (35%, of which 50% had proton beam therapy), less so in CCS and DDCS (6.6% and 5.3% respectively).
Five-year RS was 96% (93-99) for low-grade CCS, 76% (71-81) for high-grade CCS, 18% (11-29) for DDCS and 74% (58-93) for MC. Older age, DDCS histology, male gender, high deprivation and pelvic or spinal primary site conferred higher risk of death in multivariate analysis of CS overall, but only older age was significant when modelling high-grade CCS alone. Older age, male gender and higher deprivation conferred lower survival in DDCS. In multivariate analysis there was no significant difference in outcome between DDCS patients treated with surgery and chemotherapy vs surgery alone (p = 0.49).

Conclusion: This large national population-based study provides valuable data to better understand the heterogeneity of CS and inform stakeholders on patient management.

Patient characteristics, incidence and 5-year relative survival (RS) for CS patients diagnosed in England 2013-2022.