Abstract 745P
Background
Osteosarcoma is a condition which requires multimodality treatments. High dose methotrexate (HDMTX) regimens remain as standard of care, but it requires complex pharmacokinetic monitoring. This study evaluated the efficacy of non HDMTX containing regimens in patients with osteosarcoma of the extremities.
Methods
This is a retrospective review of 23 patients [Median age 20 years (Range 12-43)] who had untreated, localised osteosarcoma which was resectable, from year 2008-2018 in single institution. Kaplan-Meier and Cox regression methods were used for statistical analyses.
Results
78.2%(n=18) were male and 19.2%(n=5) were female. At diagnosis, 34.8% (n=8) had tumour >10cm. Patients underwent neoadjuvant chemotherapy followed by surgery, 56.5% (n=13) received 2 drugs regimen (IV Cisplatin 100mg/m2 D1, IV Doxorubicin 25mg/m2 D1-3 6 cycles), while 39.1%(n=9) were given 3 drugs regimen (IV Doxorubicin 50mg/m2 D1, IV Cisplatin 60mg/m2 D1, IV Ifosfamide 1000-1200mg/m2 D1-5 6 cycles). 1 patient received VIDE regimen due to initial histology reported as Ewing sarcoma. All patients received at least 3 cycles (Mean 3.6) neoadjuvant chemotherapy, and total 6-8 cycles including adjuvant chemotherapy. Limb sparing surgery was performed on all patients. 4 patients had positive margin, 9 patients yielded good histology response (≤5% viable tumour cells). After median follow up of 147 months (Range 74-172m), the median event free survival was 97.3 months. The 5 and 10 years survival rate were 56.5% and 52.2% respectively, with estimated median overall survival of 109.5 months (95% CI 92.5-126.5m). 5 local relapses and 10 distant metastasis occured. 3 patients had anthracycline induced cardiomyopathy, while 2 patients experienced severe sensory neural hearing loss. Tumour >10cm, positive surgical margin and >5% viable tumour cells post chemotherapy are predictive of unfavourable survival.
Conclusions
Non HDMTX containing regimens used in this analysis showed inferior survival to those of HDMTX containing regimens, but still offers good alternative for our institution due to scarcity of resources for MTX pharmacokinetic monitoring. Validation by larger sample size and collaboration with other centers are needed.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.