(P 216) BRAIN METASTASES IN SARCOMA: A (NOT SO) RARE EVENT. THE EXPERIENCE OF A HIGH VOLUME CENTER

Objective: Occurrence of brain metastases (BM) in patients with soft tissue (STS) and bone sarcoma (BS) is not common. Global incidence is estimated to be around 1-3% but data may differ according to histology, with alveolar soft tissue sarcoma, Ewing sarcoma, angiosarcoma and leiomyosarcoma showing the highest tendency to central nervous system spreading (up to 36%, 32%, 25% and 19% respectively). Brain involvement in sarcoma is considered an unfavorable event for prognosis, but highly variable survival rates are reported in literature.

Methods: This is a single Center retrospective study. We retrieved data of pts with STS and BS treated between 2010 and 2022 at Veneto Institute of Oncology from a retrospectively maintained database. The following data were collected: age at diagnosis, gender, primary tumor characteristics, date and location of first metastasis, time to BM, BM characteristics (number, location, edema), associated symptoms, management of BM, and survival. Pts lost at follow-up were censored at the last date known to be alive. Overall Survival (OS) was calculated with Kaplan-Meier method.

Results: Out of a total of 1870 pts, of whom 801 with advanced disease, 24 developed BM (1.3%; 3% considering only pts with advanced/metastatic disease). Pts’ characteristics are summarized in Table 1. Most frequent histotypes among pts with BM were Ewing sarcoma (16.7%), leiomyosarcoma (12.5%), and undifferentiated pleomorphic sarcoma (UPS) (12.5%). BM were detected in 4 pts (16.7%) with Ewing sarcoma, 2 pts (6.1%) with synovial sarcoma ), 2 pts (4.8%) with angiosarcoma , 2 pts (4.5%) with osteosarcoma (2pts) and 3 pts (4.0%) with UPS. Median time to onset of BM was 11 months from diagnosis and 4.6 months from the development of other metastatic sites. Most BM were diagnosed after the occurrence of symptoms (16pts, 66.6%); most associated symptoms were due to specific localisations rather than intracranial hypertension: a decline in vision and hyposthenia of the extremities (20.8% each), seizures and headache (16.7% each). In fact, only in 8 pts (33.3%) BM were associated with parenchymal edema. Sixteen pts (66.7%) developed metastasis only in the brain, 3 pts (12.5%) in the brain and cerebellum, 5 pts (20.83%) in the meninges. Half of the pts presented one single metastasis, 29.2% of pts had more than 5 sites; meningeal metastases were always widespread. [Table 2] BM were the only metastatic site for 5 pts (20.1%). Eighteen pts (75%) received at least one treatment for BM: 6 pts received only a local treatment, 6 pts received only systemic therapy and 6 pts both local and systemic therapy. Exclusive radiotherapy was performed in 5 pts, surgical resection in 4 pts, and a combination of radiotherapy and surgery in other 3 pts. Median OS from the date of brain metastasis was 2.4 months [95%CI: 1.88-NA], median OS from initial diagnosis was 17.4 months [95%CI: 12.50-NA]. At 12 months, 15 out of 24 patients have died: the probability of survival was 25.9% [95%CI: 11.98%-55.94%]. [Figure 1] No difference in OS according to sex, age and presence/absence of symptoms was found.

Conclusion: In our large series of patients with STS and BS, global incidence of BM was low, with some histological subtypes confirmed to be associated with higher risk, particularly Ewing sarcoma, synovial sarcoma, angiosarcoma, osteosarcoma and UPS. Most BM were single and amenable to local approach (surgery, radiotherapy or a combination of both). Despite best local and systemic treatment, BM still impact negatively on prognosis, with median OS from BM diagnosis being less than 3 months.