BSLD-08 OUTCOMES OF LEPTOMENINGEAL DISEASE AFTER ONLY VERTEBRAL OSSEOUS METASTASES: A REAL-WORLD ANALYSIS USING THE TRINETX DATABASE

Abstract Leptomeningeal disease (LMD) is a morbid complication of systemic cancer usually associated with brain metastases. However, vertebral bone metastases may also serve as a route for cerebrospinal fluid spread, though this pathway is less characterized. Using the TriNetX global health research network (n=133 million), we identified 7,887 adult patients with vertebral metastases from common solid tumors (lung, breast, prostate, colorectal, renal, melanoma, thyroid) who did not have brain metastases or other potential sources of LMD. Among these, 145 patients (1.9%) developed LMD following vertebral osseous metastasis alone. Breast cancer had the highest rate of LMD (3.0%), followed by colorectal (1.8%), thyroid (1.8%), and melanoma (1.7%). The median time from vertebral metastasis to LMD was 95 days (IQR 49–377), which was longer than the 60-day median (IQR 12–272) in patients who first had brain metastases before developing LMD (p<0.001). Patients whose initial metastasis was vertebral developed LMD significantly earlier than those with prior systemic metastases (median 95 vs 274, IQR 151-602, p<0.05). Those vertebral metastasis patients with LMD had shorter overall survival compared to those without (median 164 vs. 370 days, p = 0.0006; HR 0.61, 95% CI 0.46–0.81). Among those with breast cancer, the presence of LMD was associated with a substantial reduction in survival (median 170 vs. 1001 days, p<0.01). Patients with LMD were also more likely to require hospice or palliative care (39.6% vs. 22.2%, p<0.001), while those without LMD more often reported pain (67.1% vs. 52.4%, p<0.5) and emotional distress (45.8% vs. 26.4%, p<0.01). Survival after LMD diagnosis was similar between those who only had vertebral osseous metastases before LMD and those who also had brain metastases before LMD (p=0.966), reflecting a poor prognosis regardless of origin. These findings highlight vertebral metastases as a LMD source and suggest a need for heightened clinical awareness.