Brain, the last fortress of sarcoma: similar dismal outcome but discrepancy of timing of brain metastasis in bone and soft tissue sarcoma

Abstract

Background and objective: Brain metastasis is a rare but dismal event in sarcomas. However, the pattern of occurrence and the prognostic factors associated with post-brain metastasis survival (PBMS) are not yet well-characterized.

Methods: Sarcoma patients treated at one institute within 10-year period were retrospectively reviewed and those with brain metastasis were identified. The incidence of brain metastasis was demonstrated by case per person-years and cumulative incidence curves. Univariate factors associated with PBMS were analyzed.

Results: Among 611 sarcoma patients, 20 (3.3%) developed brain metastasis. Alveolar soft part sarcoma (ASPS) and osteosarcoma were the most common subtypes. Overall, the cumulative incidence was 3.9% at 5 years and 8.4% at 10 years. However, the incidence in STS patients continued to rise up to 10 years after primary diagnosis, whereas it reached a plateau in bone sarcoma patients at 3 years. Median PBMS was 1.67 months. Univariate factors associated with better PBMS included ASPS histology, initial surgical treatment, and brain irradiation for non-surgically treated patients.

Conclusion: Our study revealed a discrepancy in the timing of occurrence of brain metastasis between STS and bone sarcoma. However, patients with brain metastasis had a poor prognosis, implicating the brain as the last fortress of sarcoma.