Leptomeningeal disease in solid cancers

Leptomeningeal disease (LMD) is one of the most dreaded complications of solid and hematological malignancies and confers a poor prognosis. LMD occurs in about 5% of patients with solid cancers, most commonly in patients with breast cancer, lung cancer, and melanoma. Diagnosis of leptomeningeal disease is challenging and is dependent on the correlation of typical symptoms and signs, characteristic imaging findings, and evaluation of spinal fluid for malignant cells. The incidence of solid cancer LMD is rising due to improved survival of cancer patients and more frequent imaging. Treatment is dependent on patients' functional status, extent of systemic cancer, and availability of systemic treatment options. The landscape of treatment for solid cancer LMD is changing with the advent of novel blood-brain penetrant molecular targeted therapies and immunotherapy. More clinical trials are expected to include patients with solid tumors and LMD as novel treatment options have been developed. This chapter aims at reviewing the recent literature on LMD from solid cancers (focusing on breast cancer, lung cancer, and melanoma) and providing an algorithm that can be used to standardize our approach to management of this disease.