SURVEY-CNS: A Feasibility Study of Randomising Women and Men With HER2-Positive Metastatic Breast Cancer to Central Nervous System Surveillance Versus No Surveillance

SURVEY-CNS is a feasibility study evaluating whether women and men with HER2-positive metastatic breast cancer can be successfully recruited and randomised to a strategy of central nervous system (CNS) magnetic resonance imaging (MRI) surveillance versus standard of care (no routine CNS surveillance). Patients with HER2-positive metastatic breast cancer have a high risk of developing brain metastases. Brain metastases can cause significant symptoms, including headache, nausea, seizures, visual disturbance, motor dysfunction, and cognitive or psychological changes. Although new HER2-directed therapies have improved systemic disease control, CNS progression remains common and is associated with reduced quality of life and survival. Currently, routine brain imaging is not recommended in asymptomatic patients. Brain imaging is typically performed only when neurological symptoms develop. Observational data suggest that patients diagnosed with asymptomatic brain metastases may have better outcomes than those diagnosed after symptoms occur. However, it is not known whether a surveillance strategy is feasible or acceptable to patients. All participants in this study will undergo a baseline contrast-enhanced brain MRI. Patients without evidence of CNS metastases on the baseline scan will be randomised (1:1) to either: CNS surveillance with repeat brain MRI at 6 and 12 months, or No routine surveillance imaging (standard of care), with imaging only if clinically indicated. The primary objective is to determine whether more than 30% of eligible patients approached agree to undergo screening and randomisation. The study will approach up to 193 patients and will be considered feasible if 69 patients consent to screening with intent to randomise. Secondary objectives include: Determining the proportion of patients with previously undetected (occult) CNS metastases at baseline; Determining the incidence of occult CNS metastases during surveillance; Recording symptomatic CNS presentations; Describing management of CNS metastases, including surgery or radiotherapy. Participants will be followed for 14 months from baseline.