CMET-31. WHOLE BRAIN RADIOTHERAPY VERSUS STEREOTACTIC RADIOSURGERY IN POOR-PROGNOSIS PATIENTS WITH 1 – 10 BRAIN METASTASES: A RANDOMIZED FEASIBILITY STUDY

Abstract BACKGROUND The clinical advantage of stereotactic radiosurgery (SRS) over whole brain radiotherapy (WBRT) in patients with brain metastases and poor prognosis is controversial. To investigate the feasibility of a phase III clinical trial in a population of patients with poor prognosis, we conducted a randomized feasibility study of WBRT versus SRS. METHODS Patients with Karnofsky performance status (KPS) ≥ 70, life expectancy of 3–6 months, based on both Diagnosis-Specific Graded Prognostic Assessments and attending oncologist opinion, and 1– 10 brain metastases with a diameter ≤ 4 cm were enrolled at six Canadian cancer centers. Patients were randomly assigned to WBRT (20 Gy in 5 fractions) or SRS (15 Gy in 1 fraction). The primary endpoint was the rate of accrual. A secondary endpoint was the ratio of screened subjects to accrued subjects. This trial is registered with ClinicalTrials.gov (NCT02220491). RESULTS Between January 2015 and November 2017, 210 were screened to enroll 22 patients (9.5 screened/participant) and 20 patients were randomized. The accrual rate was 0.63 patients / month. The most common reasons for exclusion were: estimated median survival outside 3–6 months (n = 40), baseline KPS below 70 (n = 28), and > 10 brain metastases (n = 28). The median survival was 7.0 months. The overall survival was 9.5 months (n = 11) for patients who had subsequent systemic therapy, compared to 3.7 months (n = 9) in patients who had none. In both arms, the cumulative incidence of retreatment with brain radiotherapy was 40%. CONCLUSIONS Accrual was slow and the median survival was longer than expected, but a randomized trial evaluating WBRT vs SRS in patients with poor prognosis would likely be feasible by enrolling only patients with no remaining systemic therapy options.