Clinical characteristics and prognostic factors for survival in metastatic osteosarcoma, a 2004-2021 retrospective analysis of cases in SEER.

e23512 Background: Osteosarcoma is the most common primary bone malignancy, and 20% of cases are metastatic at diagnosis. Previous studies analyzing data in the SEER database up to 2004 showed no improved survival by 10-year intervals, while patients who received chemotherapy did better. Since then, there has been an introduction of new effective drugs. We aimed to analyze SEER data from 2004 to 2021 for possible survival improvement by every 5 years and potential prognostic clinical factors. Methods: We retrospectively identified metastatic osteosarcoma cases at diagnosis in SEER between 2004 and 2021. We used Kaplan-Meier to compare overall survival (OS) based on different clinical characteristics, and Cox regression to identify the factors influencing survival. Results: Of 1052 cases of metastatic osteosarcoma identified, 28% of patients were pediatric ( < 15 years old), 36% AYA (15-39 years old), and 36% adults ( > 40 years old). 60% were male and 40% were female. 80% of patients received chemotherapy, 17% received radiation treatment, and 63% received surgery to their primary tumor site. The median overall survival (mOS) for all patients diagnosed before 2010, between 2010-2015, and 2015-2021 was 16 months, 19 months and 16 months, respectively (p = 0.8). Treatment groups who received surgery vs no surgery showed mOS 28 months vs 8 months (p < 0.0001), and the groups who received chemotherapy vs no chemotherapy showed mOS 21 months vs 3 months (p < 0.0001). The group which received radiation treatment had a lower mOS than the group without radiation, with mOS 11 months vs 20 months (p < 0.0001). Cases with a primary tumor site involving the limb vs axial bones had mOS 23 months vs 10 months (p < 0.0001). Adults received more radiation (9% vs 4% AYA and 3% Peds), less chemotherapy (20% vs 33% AYA and 27% Peds) and less surgery (16% vs 24% AYA and 23% Peds). In multivariate Cox regression including age, sex, treatment type, location, subtype and year of diagnosis, we found that pediatric and AYA patients had lower risk of death (HR = 0.4, CI: 0.3-0.5 and HR = 0.4, CI: 0.3-0.6, respectively). Patients who underwent surgical treatment of the primary site had lower risk of death as well as patients who received chemotherapy (HR = 0.4, CI: 0.34-0.48 and HR = 0.48, CI: 0.4-0.59, respectively). Patients with parosteal osteosarcoma subtype had lower risk of death (HR = 0.2, CI: 0.1-0.6), whereas osteosarcoma in Paget disease of bone subtype had increased hazard (HR = 2.8, CI: 1.4-5.6) although low number of cases (n < 10). Conclusions: The mOS in patients with metastatic osteosarcoma has not changed from 2004 to 2021, similar to results before 2004. Pediatric and AYA patients have better survival than adults, likely due to higher rates of receiving chemotherapy and surgery. Radiation use showed worse survival, possibly due to a lower tendency to receive surgery or chemotherapy.