Clot composition analysis in ischemic stroke of cancer patients: a systematic review

Cancer patients are at high risk of ischemic stroke (IS) and worse outcomes. Endovascular thrombectomy (EVT) has made the analysis of retrieved clots available. This review aimed to identify studies and case reports on IS clot analysis in cancer patients (PROSPERO Registry Number CRD420251042353). The databases of PubMed/MEDLINE and SCOPUS were systematically searched for studies and case reports involving pathological analysis of clots (from EVT or autopsy) retrieved from IS patients with cancer, following the PRISMA guidelines. Studies on children, other retrieved materials, benign tumors, or where the results of cancer patients were unavailable were excluded. 23 case reports and 10 studies with larger clot numbers were included. Seventeen case reports referred to tumor embolism, 3 to cancer-related thrombosis (Trousseau syndrome), 2 to mucin embolism, and 1 to post-radiation stenosis. Most clots had an atypical white appearance, with tumor cells and mucin in tumor or mucin embolism respectively, or a platelet predominance for cancer-related thrombosis. Seven of 8 larger-scale studies reported significantly higher platelet and lower red blood cell proportions for clots in cancer patients, and 5 studies showed no increased percentages of white blood cells or neutrophil extracellular traps. The available studies were heterogeneous, and relatively small. However, preponderance of studies shows the clots of cancer patients tend to be white and predominantly platelet-rich. Atypical appearances also occur in cases of tumor or mucin embolism. These findings bear diagnostic and therapeutic implications after IS in cancer patients, including tumor work-up in platelet-rich clots and no other identifiable cause.