(P 183) A RETROSPECTIVE STUDY OF THE EFFECTS OF PATIENT, DISEASE, AND TREATMENT FACTORS ON SURVIVAL OUTCOMES IN PATIENTS WITH SOFT TISSUE SARCOMA BRAIN METASTASES

Objective: To identify which patient, disease, and treatment factors affect survival outcomes in soft tissue sarcoma (STS) patients with brain metastases (BM).

Methods: Cases of soft tissue sarcoma brain metastases between May 1996 and May 2023 were identified from the institutional prospectively collected STS database, and radiotherapy records. Patient, disease, treatment and survival data were collected from patient records.
Survival was calculated from the date of BM diagnosis, and outcomes were analysed using age, sarcoma histological subtype, tumour grade, ECOG performance status (PS), number of brain metastases, extracranial disease status, and date of BM diagnosis as putative predictor variables. Univariable analysis was performed using Kaplan Meier methodology to create survival graphs, and logrank testing to compare hazard ratios between curves. Multivariable analysis was performed using the Cox proportional hazards model. Likelihood ratios were computed by comparing 2 multivariable models, one with all predictor variables included, and another with a single variable excluded.

Results: One hundred and seventy two cases of STS with brain metastases were identified between 1996 and 2023. Median age at diagnosis of BM was 46 (range 17-89) years and 46% were female. The median time from primary diagnosis to diagnosis of BM was 18 (range 0-328) months, and 8% of patients presented with BM. BM were managed with neurosurgery in 20% (n=34) of patients, stereotactic radiosurgery in 11% (n=19), and whole brain radiotherapy in 61% (n=105). Some patients received more than one of these treatment modalities. Twenty-three percent of patients (n=39) did not receive brain-directed therapy. With a median follow up of 92.5 months, the median overall survival (mOS) for all patients was 3.75 months. On multivariable analysis of patient and disease predictor variables, survival was significantly longer in patients with alveolar soft part sarcoma (mOS 38 months, P=0.02), and significantly shorter in patients of PS 3 (mOS 1.8 months, compared with 2.4 months for PS 2, and 6.8 months for PS 0-1, P=0.02) and patients with >1 BM compared with 1 BM (mOS 3.2 months vs. 6.4 months, P=0.046) [Table 1 and Figure 1]. Patient age, the presence of extracranial disease, tumour grade, and date of BM diagnosis were not associated with significant differences in overall survival. On analysis of treatment factors, mOS was significantly longer in patients treated with stereotactic radiosurgery (SRS) compared with those that did not receive SRS (mOS 14.33 months vs. 3.52 months, P=0.0007) and in patients that had neurosurgery compared with those that did not (mOS 18.05 months vs. 3.19 months, P< 0.0001), though whole brain radiotherapy (WBRT) was not associated with significantly improved survival (mOS 3.91 months compared with 3.58 months for patients not receiving WBRT, P=0.32).

Conclusion: Patient and disease factors should be considered when deciding on treatment for STS patients with brain metastases. In this cohort, patients with alveolar soft part sarcoma and those with fewer brain metastases had a better prognosis than patients with other sarcomas and those with a higher numbers of metastases. Survival was significantly longer in patients treated with SRS or neurosurgery, though only patients with Karnofsky performance status ≥70 and appropriate intracranial disease burden (< 20cc for SRS) are eligible for these treatments, which biases survival comparisons with patients not receiving SRS or neurosurgery. Nonetheless, survival outcomes were relatively good in these patients, with an mOS of 14 months for SRS and 18 months for neurosurgery. Brain-directed therapy with neurosurgical resection or SRS should be considered for patients of good performance status, regardless of age. Further research is required into the optimal management of brain metastases in soft tissue sarcoma patients.