# Pelvic Osteosarcoma: Outcomes of Surgically Treated Patients in a Retrospective Single-Center Study

## TL;DR

This study examines survival and functional outcomes in 56 patients with pelvic osteosarcoma, finding that younger age and no metastasis improve survival, while surgical margin quality and reconstruction impact recovery.

## Contribution

The study provides updated survival data and identifies key prognostic factors in pelvic osteosarcoma management using a single-center cohort.

## Key findings

- Younger patients (≤25 years) had significantly better 5-year overall survival (68%) compared to older patients.
- Metastatic disease at any time was the strongest predictor of poor survival (5-year OS 30%).
- Achieving R0 resection was common and likely contributed to improved survival compared to historical data.

## Abstract

Pelvic osteosarcoma is a rare but highly challenging malignancy due to the complex anatomy of the pelvis and the difficulty of achieving wide surgical margins. In this retrospective single-center study of 56 patients, we evaluated survival outcomes and prognostic factors including age, metastatic status, Enneking classification, histological subtype, response to neoadjuvant chemotherapy, and the functional outcome. Overall survival reached 48% at 5 years, with younger patients demonstrating significantly better outcomes. Achieving R0 resection was common and likely contributed to improved results compared to historical cohorts. Metastatic disease remained the strongest predictor of poor survival. The mean MSTS score one year after operation was 14.1 points. These findings provide updated insight into the contemporary management and prognosis of pelvic osteosarcoma and highlight the persistent challenges associated with this aggressive tumor.

(1) Background: Pelvic osteosarcoma accounts for a small proportion of osteosarcoma cases but is associated with significantly poorer outcomes than extremity tumors. This study evaluates contemporary survival outcomes and prognostic factors in a single-center cohort. (2) Methods: We retrospectively analyzed 56 patients with primary pelvic osteosarcoma treated between 2006 and 2019. Demographic characteristics, surgical margins, adjuvant therapies, local recurrence, metastasis, survival outcomes and the Musculoskeletal Tumor Society (MSTS) Score were assessed. Kaplan–Meier analysis was performed for overall survival (OS), including subgroup analyses by age and Enneking classification. (3) Results: Median age at surgery was 24 years. R0 margins were achieved in 96.4% of cases. OS at 1, 3, and 5 years was 69%, 54%, and 48%, respectively. Younger patients (≤25 years) showed significantly improved 5-year OS (68%) compared with older groups. Enneking classification showed limited prognostic discrimination. Metastatic disease at any time strongly predicted inferior survival (5-year OS 30% vs. 66%). The mean MSTS score one year after operation was 14.1 points. Functional outcome showed marked variability and was strongly influenced by patient age, extent of resection, reconstruction strategy, and postoperative complications. Younger patients and those undergoing limited or non-acetabular reconstructions achieved superior functional results, whereas complex endoprosthetic reconstructions and revision-requiring complications were associated with reduced MSTS scores. (4) Conclusions: Pelvic osteosarcoma continues to be associated with substantial morbidity and mortality. Younger age and absence of metastatic disease are strong predictors of improved survival. Functional outcomes are typically moderate; further advances are needed to improve results.