Natural History

The natural history of a disease (e.g. a meningioma) is the course an illness takes without any intervention (i.e. any treatment).  In other words, the natural history of a meningioma is how that particular tumor behaves in an individual patient when it is just observed without any treatment.

In any given disease, when and what treatment should be administered must be based on thorough knowledge of (1) the disease’s natural history, (2) the risks of the treatment, and (3) the benefits of the treatment.  In surgical management of a meningioma patient, benefits of surgery must far outweigh the risks, and simultaneously, surgery must significantly alter the natural history, either by “curing” the meningioma when “complete” removal is achieved, or by significantly “delaying the (tumor) progression” when “partial” removal is performed, thereby prolonging the patient’s overall survival.

The literature information on meningioma’s “natural history” has been scant, and when available, the past studies were limited to the sample size of less than 100 patients.  My group at the Cleveland Clinic published the largest “natural history” paper on meningiomas in 2011.  In that study, we observed 273 meningiomas in 244 patients for a mean period of nearly 4 years.   In that time frame, 44% of the meningiomas showed growth.  Among the factors that “favored” growth in these observed meningiomas were:  (1) young age less than 60 years old, (2) absence of calcification in meningiomas, (3) T2 signal hyperintensity on MR imaging, and (4) peritumoral edema (“brain swelling” around the tumor).

What the above study indicates are the following:

• Not all meningiomas, especially if they are not causing any symptoms, require surgery at the time of initial diagnosis as only less than half (44%) show growth in 4 years.
• In patients with meningiomas that have any of the above 4 factors that favor growth, surgery should be considered either at the time of diagnosis, or when the tumor shows growth after an initial period of observation.
• If 44% of observed meningiomas showed growth in 4 years, it is reasonable to deduce that a vast majority of meningiomas will eventually grow when observed beyond 5-10 years. Therefore, in young patients, surgery may be considered at the time of diagnosis while the tumor is at its smallest size.  In brain surgery, the larger the tumor size, the higher are the surgical risks.

 

Additional reading:

The Natural History of Intracranial Meningiomas

Oya S, Kim SH, Sade B, Lee JH:  The natural history of intracranial meningiomas, J Neurosurg 114:1250-1256 (2011)