Neurological Complications of Systemic Cancer

Neurological complications of cancer are an extensive group of disorders that can be devastating for the patient. These complications are caused by invasion of the nervous system by tumor cells or by indirect mechanisms, in which case the pathogenesis often differs from that in the noncancer population. Neuroimaging and other diagnostic techniques can facilitate the diagnosis of metastatic complications but are less definitive for the latter group of disorders, which often require neuro-oncological assessment.

This issue of Seminars in Neurology brings together an expert group of neuro-oncologists to review the neurological complications of cancer and the side effects of oncological therapies. The reader will learn that with advances in oncology, neuro-oncological complications remain frequent, affecting at least one of five cancer patients. In the first article El Kamar and Posner summarize the treatment of brain metastases and the therapeutic approach to dealing with the problems that these patients develop, such as brain edema, seizures, deep vein thrombosis, headache, gastrointestinal symptoms, and depression. Chamberlain focuses the second article in the diagnosis and treatment of leptomeningeal metastases of solid tumors; it stresses the importance of determining whether there is blockage of cerebrospinal fluid flow and discusses the best treatment approach in each instance. Gabriel and Schiff address the diagnosis and treatment of epidural spinal cord compression with an update on recent data regarding the surgical management of selected patients. Jaeckle reviews the diagnosis and treatment of plexopathies in cancer patients, including a useful discussion of the features that assist in the differential diagnosis between radiation-induced and metastatic plexopathies. Colocci, Glantz, and Recht review the literature on systemic lymphoma with central nervous system involvement and describe the main risk factors for this complication; the authors propose a trial assessing efficacy of central nervous system prophylaxis in high-risk lymphoma patients. In the sixth article Béhin and Delattre discuss the neurological complications of radiation therapy, including effects on central nervous system tissue, blood vessels, and the hypothalamic-pituitary-axis. This review, along with that by Dropcho on side effects of chemotherapy, underscores the extensive variety of neurological complications that standard oncological therapy may cause. The eighth article by Saiz and Graus reveals that bone marrow and hematopoietic cell transplantation are also associated with neurological complications that often derive from coagulopathy, toxic-metabolic abnormalities, immunosuppression, and infections. The latter are specifically addressed by Pruitt, who reviews the variety of infectious complications according to specific immunological deficits and describes some rare or only recently identified syndromes such as the immune reconstitution inflammatory syndrome. Article ten by Rogers addresses cerebrovascular complications; it emphasizes that in cancer patients the pathogenic mechanisms of stroke frequently differ from those of the noncancer population and, therefore, the diagnostic and therapeutic approach also varies. In the last article Bataller and Dalmau summarize a novel set of diagnostic criteria for paraneoplastic syndromes and critically review the evidence for the existence of effective antitumor immunity in these patients; the authors also propose a general treatment strategy for paraneoplastic syndromes.

For all neurological complications of cancer, determination of the most effective treatment pathway and the effect of treatment on neurological function should be a collaborative effort between the patient's primary physician and the neuro-oncologist. Many neuro-oncological complications can be treated not only symptomatically but with definitive therapies that positively impact the patient's quality of life. I am delighted to be the guest editor of this outstanding issue of Seminars in Neurology, and I thank all the authors for their contributions.