Yield of Surveillance Imaging in Long-Term Survivors of Brain Metastasis Treated With Stereotactic Radiosurgery.

Purpose/Objective(s) Although patients with brain metastasis treated with stereotactic radiosurgery (SRS) in the definitive or post-operative setting have high rates of local control, surveillance imaging is necessary to assess for central nervous system (CNS) recurrence. Guidelines recommend magnetic resonance imaging (MRI) of the brain every three months for surveillance in asymptomatic patients post-SRS. However, optimal frequency and duration of surveillance imaging in long-term survivors is unknown. Our objective is to define the yield and cost of surveillance MRIs in long-term (> 1 year) survivors following SRS. Materials/Methods We identified a cohort of patients with brain metastases treated with SRS in the definitive or postoperative setting at a single institution from 8/2014 to 9/2019. Eligible patients had at least one-year of follow-up with absence of CNS disease failure up to and including the first MRI of the brain after 12 months from SRS. Each post-treatment MRI of the brain was assessed for disease progression or new lesions. CNS disease-free survival was time from SRS to last follow-up, death or CNS failure. Delay to diagnosis and cost per patient were estimated using hypothetical MRI schedules of 2, 3, 4 and 6 months from 1-year post-treatment while CNS disease-free. Delay to diagnosis was calculated as time from actual CNS progression to hypothetical imaging date. Medicare reimbursement median cost of $498 per MRI brain with and without contrast was used for this analysis. Results A total of 373 patients treated with SRS for brain metastasis were identified at our institution. 61 patients met eligibility criteria for inclusion in this study (median follow-up 2.50 years, median age at treatment 60 years). The median CNS disease-free survival in this population was 2.37 years from date of SRS. 15 patients (24.6%) had CNS progression at median time of 2.26 years. Of the 15 patients, 3 patients were symptomatic at recurrence. Median frequency of MRI after one year post SRS was 5.9 months. Per patient, $1156 was spent annually on MRIs of the brain after 12 months with average annual yield of 17.0%. The cost per diagnosis of CNS progression was $6806. A 2-month, 3-month, 4-month and 6-month MRI schedule had a respective estimated delay to diagnosis of 0.69 months, 1.13 months, 1.44 months and 3.19 months. The respective mean total cost of each MRI schedule per patient from one-year post-treatment while CNS disease-free was $4662, $3053, $2229 and $1380. Conclusion Patients with metastatic disease to the brain treated definitively or postoperatively with SRS without evidence of CNS recurrence at one year have a low rate of CNS failure and relatively good prognosis. Based strictly on limiting delay of diagnosis, a 2-month MRI Brain schedule is optimal in this population, albeit with a relatively small increase in financial cost over the patient's lifespan. We propose a multi-institutional study of long-term survivors with brain metastasis to strengthen these findings. Author Disclosure B.J. Rich: None. D. Kwon: None. Y.S. Soni: None. D.L. John: None. J.B. Bell: None. G. Azzam: None. E.A. Mellon: None. R. Yechieli: Support and guide school in strategic and management related matters; Toras Chaim Toras Emes, Miami FL.C. Benjamin: None. R. Benveniste: None. R.J. Komotar: None. M. Ivan: None. J. Morcos: None. T. Diwanji: None.