RMTD-01 PROGNOSTIC SIGNIFICANCE OF STABLE EXTRACRANIAL DISEASE IN PATIENTS WITH INTRACRANIAL METASTATIC DISEASE: INSIGHTS FROM A RETROSPECTIVE POPULATION-BASED STUDY Open Access

Intracranial metastatic disease (IMD) is a life-limiting complication of lung cancer, breast cancer, and melanoma. Prior research suggests prolonged survival in patients with stable extracranial disease and IMD (IMD-SE), compared to patients with progressive extracranial disease (IMD-PE). A comprehensive clinical characterization of patients with IMD-SE is lacking. This study aims to investigate clinical characteristics, outcomes, and the impact of patient and treatment factors on survival in patients with IMD-SE vs. IMD-PE.

This retrospective cohort study included patients diagnosed with primary lung cancer, breast cancer, or melanoma, and IMD in Ontario, Canada between April 1, 2010, and August 31, 2019. IMD-SE criteria included no extracranial metastases within 2 months of primary cancer diagnosis and ≥2 rounds of systemic therapy, documented in provincial records. Analyses, including Cox regression, Kaplan-Meier, and logistic regression, assessed overall survival (OS) and associations with IMD-SE. Data analysis occurred between September and December 2023.

In our analysis of 15,577 patients, 16.0% had IMD-SE, comprising 50.6% lung cancer, 40.0% breast cancer, and 9.3% melanoma. IMD-SE patients showed longer median OS from primary cancer diagnosis (27.72 months vs. 6.54 months in IMD-PE; p<0.0001) and from IMD diagnosis (4.60 months vs. 1.91 months in IMD-PE; p<0.0001). Receipt of systemic therapy and brain surgery decreased the risk of death in IMD-SE patients (HR <0.8), while lung cancer and cranial radiotherapy increased the risk. IMD-SE status was least associated with lung cancer and most associated with age <65 years, systemic therapy, primary radiation, and ≥2 rounds of cranial radiotherapy.

This study provides insights into IMD prognosis, emphasizing the importance of considering extracranial disease progression for survival predictions. Our findings enhance understanding of IMD-SE, guiding refined prognostic assessments and innovative treatments. Future studies should explore additional variables for a comprehensive understanding of factors influencing IMD-SE.