Abstract 1642P
Background
The most common subtype of bone sarcomas is osteosarcoma, for which treatment protocols are established and often used in the treatment of other subtypes of bone sarcomas. However, much less is known about the biology and appropriate treatment of these rare tumours. Our aim was to analyse the treatment results of patients (pts) diagnosed with rare subtypes of bone sarcomas, other than osteosarcoma, chondrosarcoma, Ewing sarcoma or chordoma.
Methods
In this retrospective study, we have included 49 pts (27 men, 22 women) treated in our institution between 2000-2019. Kaplan-Meier estimator with log-rank test was used for survival analysis. Overall survival (OS) was calculated from the time of diagnosis to the date of death. Median follow-up was 71.2 months (95%CI: 43.1-96.3).
Results
Median age at diagnosis was 51 years (range: 21-73). Location of the tumour was upper limb in 12 (24%) pts, lower limb in 28 (57%) and pelvis in 9 (18%). Histological subtypes were pleomorphic sarcoma in 29 pts (59%), leiomyosarcoma in 8 (16%), epithelioid haemangioendothelioma (eHE) in 7 (14%) and angiosarcoma (AS) in 5 (10%). 31 pts (63%) had high grade tumours and 1 had a low grade (2%); in the remaining pts the grade is unknown (35%). In terms of size, 18 pts (37%) had T1 tumours, 24 (49%) had T2 tumours in 7 (14%) size is unknown. 8 pts (16%) had metastases at the time of presentation. 40 pts were treated with curative intent. 22 pts had a limb sparing surgery, and 17 underwent amputation. 36 patients received chemotherapy: doxorubicin and cisplatin was the most common used scheme. During follow up, metastases were diagnosed in 29 pts, in 79% of these patients the metastases were in the lungs. At the time of analysis, 19 patients had died. 5-year OS rate for the whole group was 60% (95%CI: 46-78) and for those treated with curative intent it was 74% (95%CI: 59-92), compared to 11% (95%CI: 2-71) for those with palliative treatment. There was a significant difference in prognosis between histological subtypes (log-rank P = 0.027). Diagnosis of AS was associated with the worst outcome, as patients with this diagnosis had the highest risk of metastatic disease. On the other hand, none of the eHE pts died during the follow-up period.
Conclusions
Rare bone sarcomas are a heterogenous group of tumours and there is urgent need for new developments in their therapy based on multinational cooperation.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
P. Rutkowski: Honoraria (self), Advisory/Consultancy, Speaker Bureau/Expert testimony, Travel/Accommodation/Expenses: BMS, MSD, Novartis, Roche, Pierre Fabre, Amgen, Pfizer, Eli Lilly, Sanofi and Blueprint Medicines. All other authors have declared no conflicts of interest.