The Extent of Necrosis in Brain Metastases May Predict Subtypes of Primary Cancer and Overall Survival in Patients Receiving Craniotomy

SIMPLE SUMMARY: Knowledge regarding the character of necrosis in brain metastases from different primary cancer subtypes, as well as its impact on patient survival post-craniotomy, remains unknown. We performed a retrospective analysis on 145 BMs and found that lung cancers presented with a generally larger area of necrosis. Further, moderately abundant necrosis to tumor ratio appeared to confer better overall survival versus highly abundant, or even sparse necrosis. Findings of this study indicate that necrosis to tumor ratio in brain metastasis may predict subtypes of primary cancer and have potential as a biomarker for disease prognostication. ABSTRACT: Although necrosis is common in brain metastasis (BM), its biological and clinical significances remain unknown. We evaluated necrosis extent differences by primary cancer subtype and correlated BM necrosis to overall survival post-craniotomy. We analyzed 145 BMs of patients receiving craniotomy. Necrosis to tumor ratio (NTR) was measured. Patients were divided into two groups by NTR: BMs with sparse necrosis and with abundant necrosis. Clinical features were compared. To investigate factor relevance for BM necrosis, multivariate logistic regression, random forests, and gradient boosting machine analyses were performed. Kaplan–Meier analysis and log-rank tests were performed to evaluate the effect of BM necrosis on overall survival. Lung cancer was a more common origin for BMs with abundant necrosis (42/72, 58.33%) versus sparse necrosis (23/73, 31.51%, p < 0.01). Primary cancer subtype and tumor volume were the most relevant factors for BM necrosis (p < 0.01). BMs harboring moderately abundant necrosis showed longer survival, versus sparse or highly abundant necrosis (p = 0.04). Lung cancer BM may carry larger necrosis than BMs from other cancers. Further, moderately abundant necrosis in BM may predict a good prognosis post-craniotomy.