Impact of Thrombocytopenia on Intratumoral Hemorrhage in Brain Metastases Treated with Stereotactic Radiosurgery

Introduction: Complications related to intracranial intratumoral hemorrhage (ITH) in patients treated with stereotactic radiosurgery (SRS) are rare and often require expectant management. The impact of thrombocytopenia on ITH risk in brain metastases (BM) treated with SRS remains uncertain.
To assess the incidence of ITH in patients undergoing SRS and evaluate the impact of thrombocytopenia.

Methods: We conducted an IRB-approved, retrospective review of 241 consecutive patients with 1,758 brain metastases (BMs) who were treated with stereotactic radiosurgery (SRS) from January 1, 2020, to December 31, 2021. Pre- and post-procedure MRIs, including T1-weighted and SWI/GRE sequences (microhemorrhage-sensitive), were evaluated by a neuroradiologist. Patients who received anticoagulant therapy (n=51; 479 metastases) were excluded.

Results: Among 190 patients (1279 metastases), 125 (65.8%) had pre-Gamma Knife (GK) hemorrhage, with 99.2% (124) exhibiting persistent post-treatment hemorrhage. Overall, 76.3% (145) of the cohort experienced post-GK hemorrhage. Of the 65 patients without pre-GK hemorrhage, 32.3% (21) developed new post-GK ITH. In patients with thrombocytopenia (35 patients, 147 targets, platelet counts < 150), 57.1% had persistent post-GK hemorrhage, and 8.6% developed new post-GK hemorrhages. Antiplatelet therapy was noted in 44 patients (23.2% of the cohort), with no significant association with increased post-GK ITH risk (OR: 0.99, 95% CI: 0.93–1.06, p = 0.92). Multivariate GEE analysis did not confirm thrombocytopenia as a significant risk factor (OR: 0.99, 95% CI: 0.93–1.07, p = 0.95), and moderate thrombocytopenia was similarly not significant (OR: 1.0, 95% CI: 0.88–1.13, p = 0.97). Pre-GK hemorrhage was identified as a significant predictor of post-GK ITH (OR: 2.38, 95% CI: 2.26–2.41, p < 0.001). Primary tumor histology did not influence hemorrhage risk.

Conclusion : Although thrombocytopenic patients showed higher post-GK hemorrhage frequency, multivariate analysis on clustered data did not find it significant. Antiplatelet therapy was not associated with increased ITH risk. Further research is necessary to better understand the role of platelet counts in post-SRS outcomes.