Age as a prognostic factor in osteosarcoma: Survival analysis.

Abstract

10074 Background: Studies comparing survival between adult and paediatric population with osteosarcoma are scarce and contradictory. Generally adults were excluded from analysis in historical series. End Point: evaluate age as prognostic factor in ostosarcomas IIb treated exclusively by a multidisciplinary group in a single institution. Methods: 132/278 patients with histological diagnosis of osteosarcoma IIb were selected. All were treated exclusively in our hospital from July 1988 until December 2010. Patients 17 years old or younger were considered paediatric. They all received presurgical chemotherapy with the same scheme: ifosfamide + doxorrubicin + high dose methotrexate. Univariate analysis was made (Fischer exact test). Survival was calculated wih Kaplan-Meier actuarial method. Curves were compared with log rank test. Multivariate Cox analysis was made. Results: Median age was 19.6 years (std: 9,1; range 5-58). Adults: 77, children: 55. No differences were detected between the two age groups regarding: elevated alkaline phosphatase, kind of surgery (amputation vs. limb sparing), relapse site (lung, local, other), necrosis greater than 90% or number of lung resections. There was a tendency towards axial localization in adults (p=0.05). No paediatric patient had inadequate medical intervention, but it was present in 14.3% of adults (p=0.002). 5 year Overall survival (5y OS) in children was 85,2% compared with 61,8% in adults (p=0.005); Disease free survival (DFS) had a non significant tendency to be better in children (69.6% vs. 51,3%). Variables associated with worse OS were: axial location (p=0.01), elevated alkaline phosphatase (0.003), amputation (p=0.008), local relapse or systemic non-lung metastasis (p= 0.001), necrosis less than 90% (0.001). Multivariate Cox analysis showed association between OS and paediatric population (p=0.01) and necrosis greater than 90% (p=0.001), while DFS was associated with necrosis greater than 90% (p=0.01) and elevated alkaline phosphatase (p=0.05). Conclusions: Paediatric population presents better survival compared to adults in our institution. Differences in tumour biology and in the mode of presentation related to age may be the explanation.