The Use of Radiotherapy in Leptomeningeal Carcinomatosis: A Systematic Review and Random-Effects Proportions...

Objective: Leptomeningeal carcinomatosis (LMC) is a rare but devastating complication of advanced cancer, particularly in patients with breast and lung malignancies. This systematic review provides a descriptive synthesis of radiotherapy approaches used in patients with leptomeningeal metastases, with a quantitative proportions meta-analysis focused on treatment-related toxicity. Materials and methods: A systematic search was conducted in PubMed, Scopus, and the virtual health library (BVS) databases following PRISMA 2020 guidelines. Studies including patients diagnosed with LMC and treated with RT were selected. Outcomes included overall survival (OS), adverse events (toxicities), and functional response. Results: A total of 39 studies comprising 2822 patients were included; the most frequent primary tumors were lung (n = 1337) and breast (n = 990) cancers. The mean time from cancer diagnosis to LMC was 22.4 months. Radiotherapy regimens included whole-brain radiotherapy (WBRT, n = 1054), craniospinal irradiation (CSI, n = 148), and focal RT (n = 27); RT was administered alone or in combination with systemic treatments. Toxicity was reported in 462 patients, primarily fatigue (n = 115), nausea/vomiting (n = 72), and hematological events (notably in CSI). The pooled toxicity prevalence was 50.8% (95% CI, 26.1-75.4; I² = 96.1; p < 0.0001) for all RT modalities, and 31.6% (95%CI, 15.0-50.8; I² = 90.7; p < 0.0001) for WBRT. CSI toxicity estimates were based on a limited number of studies and did not reach statistical significance, and should therefore be interpreted as exploratory. Mean OS from LMC diagnosis was 18.2 weeks; OS by treatment was 21.5 weeks and 20.3 weeks, for RT by itself and combined, respectively. Conclusions: LMC predominantly affects patients with advanced-stage lung and breast cancers and presents with variable clinical timelines and functional impairment. Radiotherapy represents a frequently utilized and clinically important component of the palliative management of leptomeningeal disease, particularly for symptom control and neurological stabilization, rather than a treatment associated with superior survival outcomes. Prognosis is more closely linked to patient-specific factors than to treatment type. Radiotherapy toxicity is prevalent; however, most are categorized as type 1 toxicities with insignificant to little damaging effects on patients.