Whole brain radiotherapy (WBRT) for brain oligometastases has potential impact on neurocognitive function without a survival benefit. This study assesses outcome of a formal WBRT avoidance policy in this patient subgroup.
Patients referred for RT with brain oligometastases were recorded prospectively between January2010-February2017. Brain oligometastases were defined as 1-4 brain metastases; then expanded to 5-10 in February2016. Patients had WBRT Avoidance approach followed by MRI surveillance every three months. Survival was measured from date of initial CNS treatment. Outcomes of overall survival(OS), progression-free survival(PFS), initial local site progression-free survival(i-PFS) and WBRT-free survival were calculated using the Kaplan-Meier method.
166 patients managed with a median follow-up for survivors of 13months. Number of brain metastases was solitary (101), 2-4 (54) and 5-10 (11). Tumour sub-sites included Non-Small Cell Lung Cancer (63), Melanoma (28), Breast (25), Colorectal (18), Renal (16) and others (16). Initial management included surgery alone(28), surgery followed by cavityRT(74), Stereotactic Radiosurgery(47), focal Volumetric Modulated Arc Therapy(VMAT) (26) and systemic targeted therapy alone (13).
93 patients are deceased with medianOS of 15months (95%CI:10.8–19.2). Death was attributable to extracranial disease in 76% patients, or neurological in 24% patients. 83patients have CNS relapse with median PFS of 11months (95%CI:6.7–15.3). Relapse pattern was predominantly distant brain(69 relapses).
i-PFS with RT was 90% at 12 months. WBRT was utilised in only 24 patients, with 83% patients free of WBRT at 12 months. Nmetastases(p=0.04), symptomatic extracranial disease(p=0.04) and early CNS relapse within 6 months(p<0.01) had worse survival; while tumour sub-site(p=0.08), age(p=0.60), neurological death(p=0.60) were not associated with OS.
WBRT Avoidance with MRI surveillance is feasible and acceptable for patients with limited brain metastases. The OS, PFS and i-PFS were acceptable with focal therapy alone, and associated with a low rate of subsequent WBRT or later neurological death.