(P 81) OUTCOMES DATA FOR OSTEOSARCOMA PATIENTS OVER AGE 60

Objective: Osteosarcoma has an understudied second peak in incidence occurring in older adults over age 60. While outcomes and prognostic factors have been well-studied in younger patients, there is limited data on the clinical characteristics of osteosarcoma in the older adult population. This retrospective study aimed to investigate the clinical features, management strategies, outcomes, and factors impacting survival outcomes in patients aged 60 years and older diagnosed with osteosarcoma at a large academic cancer center since 2015. By analyzing this cohort of older adults with osteosarcoma, we sought to better understand the unique aspects of this disease in an aging population and identify potential opportunities to optimize care for this underrepresented patient group.

Methods: A retrospective chart review was conducted at a single high-volume sarcoma center to evaluate outcomes in older patients with osteosarcoma diagnosed and treated since 2015. Eligible patients were aged ≥60 years with either metastatic or localized osteosarcoma. Data collected from chart review included age, Eastern Cooperative Oncology Group (ECOG) performance status, treatment received (chemotherapy or best supportive care), and outcomes such as median progression-free survival (mPFS) and median overall survival (mOS). Survival analyses were performed using the Kaplan-Meier method, and differences in survival were assessed using the log-rank test. Subgroup analyses were conducted based on age, ECOG status, and the presence of secondary osteosarcoma arising from prior radiation therapy or Paget’s disease. A multivariate Cox proportional hazards model was used to analyze progression-free survival (PFS) and overall survival (OS), adjusting for ECOG performance status, age, gender, and secondary osteosarcoma.

Results: In this retrospective analysis of 35 osteosarcoma patients over 60 years old (Table 1 for patient characteristics), the median overall survival (mOS) was 1.66 years, and the median progression-free survival (mPFS) was 1.95 years. There was no significant difference in PFS and OS between those who received chemotherapy and those who did not (Figure 1A, 1B). Patients with secondary osteosarcoma had significantly worse outcomes (mOS 0.66 years vs. 2.68 years, p=0.019 (Figure 2). Patients with an ECOG score of 0 at diagnosis had better survival outcomes compared to those with scores of 1 or 2 (OS at 6 years: 25%, 5%, and 0%, respectively, p=0.023). Age did not significantly impact PFS or OS. A multivariate analysis showed that an ECOG score of 1 and the presence of secondary disease were independent predictors of worse outcomes

Conclusion: Osteosarcoma, a rare and aggressive bone cancer, presents significant challenges for older patients, with poor outcomes and limited data hindering effective treatment strategies. Current evidence suggests no clear benefit from chemotherapy for older osteosarcoma patients, especially those with poor performance status, as outcomes are generally worse. The benefit of chemotherapy for patients with an ECOG performance status of 1 remains uncertain, highlighting the need to evaluate the appropriateness of chemotherapy in this group due to potential side effects and possibly marginal benefit.
A randomized prospective clinical trial is needed to better understand the benefits of chemotherapy in older osteosarcoma patients and to test novel therapies with a more favorable risk-benefit profile. Additionally, secondary sarcomas, such as those from prior radiation therapy or Pagett’s disease, have worse survival rates, indicating a need for further investigation into their distinct biological mechanisms. However, the current evidence has limitations. The retrospective analysis involved a small cohort from a single high-volume sarcoma center, limiting generalizability. Including metastatic patients, who typically have worse outcomes, may have skewed the data and underestimated chemotherapy's benefits in localized disease. These limitations highlight the need for larger, multi-center prospective studies to more accurately assess the role of chemotherapy and other treatment modalities in older osteosarcoma patients.