2327 - Beyond Palliation: Survival Advantage of Definitive Primary Tumor Treatment In Oligometastatic Sarcoma

Purpose/Objective(s):

To evaluate the association between primary tumor treatment strategies and prognosis in patients with oligometastatic sarcoma.

Materials/Methods:

We conducted a population-based study using the Surveillance, Epidemiology, and End Results (SEER) database, including patients diagnosed with sarcoma between 2000 and 2020. Oligometastatic disease was defined as the presence of 1-3 SEER-recorded organ-specific metastatic sites at diagnosis, including lung, liver, bone, or brain. Treatment strategies were extracted and categorized based on receipt of surgery, radiotherapy, and systemic therapy. Primary endpoint was overall survival (OS) and estimated using the Kaplan-Meier method with log-rank tests. Uni- and multivariable Cox proportional hazards regression analyses were performed to identify independent prognostic factors.

Results:

A total of 4,720 patients with oligometastatic sarcoma were included. Most patients were aged =60 years (49.3%) with a balanced sex distribution. Lung metastasis was the most common site (64.5%), followed by liver metastasis (36.1%), and the majority had a single metastatic site (75.7%). Leiomyosarcoma was the predominant histologic subtype (26.9%), followed by sarcoma NOS (23.1%) and stromal sarcoma (14.5%). Median overall survival (mOS) for the entire cohort was 11 months (95% CI 11-12). Multivariable Cox analysis demonstrated that older age (HR_=60yrs 1.86, 95% CI 1.63-2.12; P<0.001), higher tumor grade (HR_{grade 3-4} 1.80-1.92; P<0.001), and increased metastatic burden (HR_{2 sites} 1.75, 95% CI 1.46-2.10; P<0.001; HR_{3 sites} 3.22, 95% CI 2.27-4.56; P<0.001) were independently associated with prognosis. Surgery (HR 0.50, 95% CI 0.46-0.54; P<0.001), radiotherapy (HR 0.73, 95% CI 0.67-0.79; P<0.001), and chemotherapy (HR 0.48, 95% CI 0.45-0.52; P<0.001) were each independently associated with improved survival. Survival outcomes differed significantly according to treatment strategy. A significantly longer mOS was observed with surgery plus chemotherapy compared with chemotherapy alone (mOS 21.0 vs 14.0 months, P<0.0001). In contrast, surgery combined with radiotherapy yielded survival comparable to chemotherapy alone (mOS 14.0 vs 14.0 months, P=0.49), and the addition of radiotherapy to surgery plus chemotherapy did not provide additional survival benefit (mOS 23.0 vs 21.0 months, P=0.50).

Conclusion:

In patients with oligometastatic sarcoma, definitive treatment of the primary tumor with surgery, with or without radiotherapy, was associated with improved survival compared with palliative systemic therapy alone, supporting a role for local therapy in this setting.