# Epidemiology and Prognosis of Patients With Osteosarcoma at Different Primary Sites: A SEER Population‐Based Study

## TL;DR

This study compares the incidence and survival outcomes of osteosarcoma patients based on tumor location, finding that peripheral-site tumors have better prognosis than central-site tumors.

## Contribution

The study provides new insights into the epidemiology and prognosis of osteosarcoma by analyzing primary anatomical sites using a large population-based database.

## Key findings

- Peripheral-site osteosarcoma has better 5-year survival and cancer-specific survival than central-site osteosarcoma.
- Surgery is a significant prognostic factor for both central and peripheral osteosarcoma patients.
- Age, stage, histologic grade, and treatment type are key factors affecting cancer-specific survival.

## Abstract

Osteosarcoma is a primary bone malignancy with a known bimodal age distribution. However, epidemiological patterns based on precise primary anatomical sites are not well characterized. This population‐based study analyzed the Surveillance, Epidemiology, and End Results (SEER) database to compare the incidence and clinical features of central‐site versus peripheral‐site osteosarcoma across different age groups.

This study aimed to compare the incidence characteristics of peripheral and central‐site osteosarcoma (OS) and to explore the impact of different primary sites on the prognosis of patients with OS.

Patients diagnosed with OS (1975–2019) were selected from the SEER databases. The different primary sites, diagnosis time, and incidence of OS were described statistically. A 1:1 propensity score matching (PSM) was used to adjust for clinical characteristics and treatment. Kaplan–Meier curves were used to compare overall survival and CSS of peripheral and central‐site OS before and after matching. Univariate and multivariate Cox models were used to investigate prognostic factors for CSS in both groups.

A total of 3129 patients were included (899/28.73% central‐site OS, 2166/69.22% peripheral‐site OS, 64/2.05% other‐site OS). After PSM, central‐site OS had lower overall survival and CSS than peripheral‐site OS (5‐year overall survival, 0.415 vs. 0.468; 5‐year CSS, 0.454 vs. 0.555). Multivariate analysis revealed that age (p = 0.010), primary site (p = 0.039), historical SEER stage (regional, p = 0.012; distant, p < 0.001), histologic grade (grade III, p = 0.014; grade IV, p = 0.009), surgery (p < 0.001), and radiotherapy (p = 0.005) were significant factors for CSS. Subgroup analyses adjusting for these factors showed better CSS in peripheral‐site OS patients.

The incidence of central‐site OS is lower than that of peripheral‐site OS, while the prognosis of patients with peripheral‐site OS is more favorable than that of patients with central‐site OS. Surgical intervention is a cornerstone in the management of OS and is effective for both central‐site and peripheral‐site OS.