Prognostic Model for Intracranial Progression after Stereotactic Radiosurgery: A Multicenter Validation Study

Abstract

Stereotactic radiosurgery (SRS) is a standard of care for many patients with brain metastases. To optimize post-SRS surveillance, this study aimed to validate a previously published nomogram predicting post-SRS intracranial progression (IP). We identified consecutive patients completing an initial course of SRS across two institutions between July 2017 and December 2020. Patients were classified as low- or high-risk for post-SRS IP per a previously published nomogram. Overall survival (OS) and freedom from IP (FFIP) were assessed via the Kaplan–Meier method. Assessment of parameters impacting FFIP was performed with univariable and multivariable Cox proportional hazard models. Among 890 patients, median follow-up was 9.8 months (95% CI 9.1–11.2 months). In total, 47% had NSCLC primary tumors, and 47% had oligometastatic disease (defined as ≤5 metastastic foci) at the time of SRS. Per the IP nomogram, 53% of patients were deemed high-risk. For low- and high-risk patients, median FFIP was 13.9 months (95% CI 11.1–17.1 months) and 7.6 months (95% CI 6.4–9.3 months), respectively, and FFIP was superior in low-risk patients (p < 0.0001). This large multisite BM cohort supports the use of an IP nomogram as a quick and simple means of stratifying patients into low- and high-risk groups for post-SRS IP.

Determinants of Symptomatic Intracranial Progression After an Initial Stereotactic Radiosurgery Course

“…The same cohort of patients were used for prior studies of other prespecified clinical endpoints. 12 , 13 Informed consent waiver was granted because de-identified data were used. Exclusion criteria included age <18 years at time of SRS as well as prior SRS.…”

“… 7 , 8 , 9 After SRS, monitoring of neurologic symptoms and imaging with magnetic resonance imaging (MRI) is essential for identifying intracranial progression (ITCP) and to direct further treatment. 10 To this end, our prior work identified patients at high risk for ITCP 11 , 12 as well as the degree to which ITCP correlates to OS. 13 However, the incidence, prognostic significance, and clinical parameters associated with neurologic symptoms at post-SRS ITCP remain poorly characterized.…”