Osteosarcoma survival and its associated factors among adults managed at Uganda cancer institute.

Abstract

Background: Osteosarcoma is the most common primary malignant bone tumor and poses significant treatment challenges in low-resource settings. While 5-year survival rates of 60–80% have been achieved in high-income countries through multimodal therapy, outcomes in sub-Saharan Africa remain markedly worse. At Uganda Cancer Institute (UCI),no survival data exist for adults (≥18 years) with osteosarcoma, representing a critical knowledge gap that limits evidence-based care planning for this age group. Objectives: To determine the 5-year overall survival rate and identify factors independently associated with survival among adults with osteosarcoma managed at UCI between 2010 and 2020. Methods: This was a retrospective cohort study of 98 adults with histologically confirmed osteosarcoma treated at UCI between -anuary 2010 and December 2020. Vital status was ascertained from medical records supplemented by telephone follow-up. Survival was estimated using the Kaplan-Meier method. Univariable and multivariable Cox proportional hazards regression were used to identify factors associated with survival. Results: Ninety-three patients were included in the survival analysis, contributing 2,579 person-months of follow-up with 68 deaths (73.1%). The 5-year overall survival was 24.2% (95% CI: 15.5%–33.9%) and median overall survival was 18.0 months (95% CI: 13.1–28.7). Survival declined steeply in the first two years, with 1-year and 2-year survival of 62.7% and 43.3% respectively. In the final stratified multivariable Cox model, three independent predictors were identified: receipt of neoadjuvant chemotherapy (aHR=0.42, 95% CI: 0.22– 0.82, p=0.011); ECOG performance status 3 (aHR=2.27, 95% CI: 1.07–4.82, p=0.033) and ECOG 4 (aHR=3.11, 95% CI: 1.26–7.67, p=0.014) compared to ECOG 1; and low tumor grade compared to high grade (aHR=0.40, 95% CI: 0.19–0.83, p=0.014). Conclusion: Adults with osteosarcoma at UCI experience very poor survival, substantially below global benchmarks. Neoadjuvant chemotherapy is the single most important modifiable determinant of survival. Interventions to improve timely access to neoadjuvant chemotherapy, optimize patient functional status prior to treatment, and reduce treatment abandonment are urgently needed to improve outcomes in this setting.