Radiotherapy for intramedullary, leptomeningeal and epidural metastases: outcomes of an unusual and ominous complication.

[PURPOSE] Non-osseous intraspinal cord canal metastases (ISCM)-intramedullary, leptomeningeal and epidural metastases-are unusual complications with dismal prognosis. This study assessed clinical outcomes, local control (LC) and overall survival (OS) after conventional palliative three-dimensional conformal radiotherapy (3DCRT).

[METHODS/PATIENTS] We retrospectively reviewed ISCM treated with 3DCRT between 2012 and 2023. Clinical outcomes were evaluated at baseline and one month after radiotherapy using Eastern Cooperative Oncology Group (ECOG), neurological status by Modified McCormick (MMC) scale, analgesic response, and sphincter control. LC, OS and prognostic factors were explored.

[RESULTS] Thirty-seven cases were included. The median follow-up (FU) was 5.2 months (1.6-8.4). Median age was 59 years (51-63). Intramedullary metastases represented 62% of cases and leptomeningeal and epidural metastases (LEM) 38%. Most patients (73%) received 30 Gy/10 fractions or 20 Gy/4-5 fractions and 27% received 8 Gy single fraction. At one month, 62% of patients showed ECOG improvement or stability, 20% achieved full neurological recovery, 83% experienced pain relief, and 62% preserved sphincter function. No grade 3 toxicity was observed. Radiological evaluation at a median of 59 days showed complete disappearance in 5%, partial reduction in 30%, no changes in 14%, and 51% had no imaging FU. Median OS was 6.6 months (95% CI 3.4-9.9). LEM, small cell lung cancer (SCLC), and baseline MMC grade 3-5 showed worse median OS (3.2, 5.2 and 2.7 months, respectively).

[CONCLUSIONS] Patients with ISCM may benefit from palliative 3DCRT, particularly in terms of neurological and functional stability or improvement, along with pain relief. Independent unfavorable factors for OS are LEM, SCLC, and poor baseline MMC grade.