Selective Internal Radiation Therapy in Breast Cancer Liver Metastases: Outcome Assessment Applying a Prognostic Score

SIMPLE SUMMARY: Selective internal radiation therapy (SIRT) is a treatment option for patients with breast cancer and liver metastases. However, there are currently no established factors to decide whether a certain patient will likely benefit from this treatment. This study analyzed the overall survival (the time from treatment to the patient’s death) in 38 patients with a total of 42 radioembolization procedures. Among all investigated factors, two variables were able to predict the outcome after radioembolization: The clinical performance status (ECOG) and the presence of elevated laboratory parameters that are markers of the liver damage (ALT, AST) before the start of the treatment. If none of these two risk factors was present, patients showed favorable outcome (average overall survival of 19.2 months). If both factors were present, overall survival after treatment was unfavorable (average of 2.2 months). In the future, this risk adapted prognostic score might help to elucidate which individual patient benefits from radioembolization. ABSTRACT: Selective internal radiation therapy (SIRT) is a therapy option in patients with breast cancer liver metastasis (BCLM). This analysis aimed at identifying a prognostic score regarding overall survival (OS) after SIRT using routine pretherapeutic parameters. Retrospective analysis of 38 patients (age, 59 (39–84) years) with BCLM and 42 SIRT procedures. Cox regression for OS included clinical factors (age, ECOG and prior treatments), laboratory parameters, hepatic tumor load and dose reduction due to hepatopulmonary shunt. Elevated baseline ALT and/or AST was present if CTCAE grade ≥ 2 was fulfilled (>3 times the upper limit of normal). Median OS after SIRT was 6.4 months. In univariable Cox, ECOG ≥ 1 (hazard ratio (HR), 3.8), presence of elevated baseline ALT/AST (HR, 3.8), prior liver surgery (HR, 10.2), and dose reduction of 40% (HR, 8.1) predicted shorter OS (each p < 0.05). Multivariable Cox confirmed ECOG ≥ 1 (HR, 2.34; p = 0.012) and elevated baseline ALT/AST (HR, 4.16; p < 0.001). Combining both factors, median OS decreased from 19.2 months (0 risk factors; n = 14 procedures) to 5.9 months (1 factor; n = 20) or 2.2 months (2 factors; n = 8; p < 0.001). The proposed score may facilitate pretherapeutic identification of patients with unfavorable OS after SIRT. This may help to balance potential life prolongation with the hazards of invasive treatment and hospitalization.