Front. Neurol., 04 March 2015 | doi: 10.3389/fneur.2015.00040
Concurrence of multiple sclerosis and brain tumorsDomenico Plantone, Rosaria Renna, Emilia Sbardells, Tatiana Koudriavtseva
Multiple sclerosis (MS) is a chronic demyelinating inflammatory disease of the central nervous system (CNS) with multi-factorial pathogenesis that includes genetic and environmental factors. A primary brain tumor is a neoplasm developing from the cells of the brain. There is high heterogeneity of primary brain tumors (about 100 different types); however, most of them develop from the glial cells.
Although several types of brain tumors have been widely described in association with MS, including astrocytoma, oligodendroglioma, and glioblastoma, it is not clear whether their occurrence is accidental or consequent to causal events. Moreover, it is not completely defined if MS and brain tumors, when associated, have a different course. The true incidence of brain tumors in MS patients is difficult to define because the diagnosis of a brain tumor in MS patients may seem more frequent than in the general population due to frequent neuroimaging scans performed in these patients. At the same time, pseudo-tumoral MS lesions may resemble gliomas, and conversely, early stage gliomas may resemble MS. Brain tumors in MS patients may be diagnosed later or even post-mortem, especially in patients with progressive MS, since the new symptoms may be attributed to the gradual clinical progression of MS rather than to the slow growing of tumor itself. A recent study reported that MS patients have a decreased overall cancer risk, but an increased risk for brain tumor. If immunosuppressive treatment for MS might promote cancerogenesis is still matter of debate, it is difficult to explain on this basis why MS patients have a decreased overall cancer risk and an increased risk only for brain and genitourinary tract tumors. A successive systematic analysis showed no increased or decreased risks for glioma in MS patients, while an increased risk was found for meningioma, as a result of incidental findings. Moreover, several autoimmune diseases influence negatively the survival in glioma and meningioma, likely due to pre-existent disability or treatment limitations.
Brain tumors in their own right are a diagnostic challenge, but in MS this is made doubly difficult, since imaging appearances of brain tumours, pseudo-tumoral lesions and large MS lesions can be indistinguishable.
So is it simple coincidence or is there reasonable cause to suspect an association?
In this article they discuss the possibility of a hereditary or acquired cause stimulating tumorous transformation:
- the increased division of cells induced by MS remyelination leading to transformation (the production of growth factors in an effort to repair the damage having an unexpected side effect)
- alterations in innate immunity-related genetic regions have been associated with increased risk of gliomas
- a common viral mechanism in both MS and tumors - the human polyomavirus JC virus (JCV) has been linked to both MS and glioblastoma multiforme; a form of high-grade brain tumor