Point/Counterpoint: Intrathecal therapy for patients with leptomeningeal metastases from solid tumors

Intrathecal pharmacotherapy is recommended by the EANO ESMO1 and NCCN guidelines2 for the treatment of patients with leptomeningeal metastases from solid tumors with tumor cells in the cerebrospinal fluid (CSF) or with linear imaging presentation (Figure 1). Yet, this therapeutic approach remains controversial, and in a survey conducted largely in Europe and published in 2017, 23 participants (10%) declared never using intrathecal therapy.3 Intrathecal chemotherapy plus systemic therapy of choice was superior to systemic therapy alone for local control in a randomized trial in patients with breast cancer and newly diagnosed leptomeningeal metastasis,4 but evidence for its role beyond this trial remains questionable. Here we review the main arguments for or against the intrathecal approach in an era where the role of MRI screening is increasing, allowing earlier detection of CNS metastases including leptomeningeal metastases in patients with good general condition, and where novel pharmacological interventions have become available.