MENINGIOMA

Natural History and Treatment Options

 

Background

Meningioma is a type of benign brain tumour that develops from the membrane that surrounds the brain and spinal cord. Most meningiomas (90%) are considered benign (not cancerous) and grow slowly over time. However, the word “benign” can be misleading, as some tumours arise from “tricky” locations that constrict and affect the brain, leading to disability and even life-threatening symptoms.

In general, meningiomas are more common among females, and the incidence increases with advancing age. Uncommon malignant meningioma tends to be more common among men.

Most meningiomas are asymptomatic and are detected incidentally following radiological investigation for other unrelated clinical presentations. Depending on the location of the meningioma and the surrounding brain structures that may be affected, patients can present with a variety of symptoms, ranging from headache, blurred vision, double vision, speech deficit, limb weakness or even seizures.

 

Natural History

The natural history of untreated meningioma is not clear. In the past, most patients with meningioma presented with neurological symptoms due to large tumors causing mass effect. Recent advances in neuroimaging and its wide availability have led to increased detection of small incidental lesions and the inherent dilemma in recommending treatment options for asymptomatic patients. Understanding the natural history of meningioma is critical, as it forms the basis for treatment.

 

Size

Tumour size affect treatment recommendation. Larger tumour size is more likely to cause symptoms and therefore early surgical intervention. A review of the published series identified that larger initial tumor size predicts subsequent growth and the potential for treatment recommendation. In general, meningiomas larger than 4 cm are likely to eventually cause neurological symptoms. Asymptomatic tumors less than 3cm may be closely observed with regular radiological surveillance.

 

Growth rate and tumor doubling time

Studies of the natural history of meningiomas have found that most tumors grow very slowly. These were conducted on patients with incidental tumors with many remain asymptomatic during the follow-up period. Current literature evidence suggests meningiomas have an annual growth rate of 0.7 - 4mm per year and increase 3.6% - 20.4% per year in volumetric measures. This means a meningioma can double in size every 9 to 10 years. However, inherent limitations of these natural history studies are characterised by selection biased towards elderly patients subjected to observation and short follow-up period.

Risk Factors that predict tumor growth

There are several factors that have been identified to be associated with a greater tendency of tumour growth. These include:

  • Larger tumour size at the time of diagnosis (>25mm)

  • Younger patient age (<60 years)

  • The presence of brain swelling around the meningioma

  • Certain location within the skull from which the meningioma arises, especially “sphenoid ridge”

  • Certain tumour characteristic present on the MRI scan (i.e., presence of intratumoral T2 hyperintensity)

Treatment Options

Management of meningiomas depends on their natural history, growth, and the risk associated with intervention.  In general, there are three treatment options: observation, radiotherapy, or surgery. Based on available data, management recommendation must consider tumor size, location, associated brain swelling, patient’s age, and medical co-morbidities.

  • Meningioma that are more than 3cm in size should be considered for surgical excision, as they are likely to become symptomatic as they enlarge.

  • Meningioma that demonstrates a high growth rate (≥2mm/year) on serial imaging should be considered for surgical excision, especially in younger patients in good health.

  • Meningioma that becomes symptomatic at any point during the follow up period should be considered for surgical intervention.

  • For elderly patients, meningiomas often demonstrate a slower growth pattern, which in conjunction with increased operative morbidity, may necessitate a more conservative approach.

  • For younger patients, asymptomatic tumors (smaller than 3cm) may be observed with regular radiological surveillance. Consideration for observation need also to consider the potential higher-grade meningiomas, in which subsequent delay in intervention may result in potentially higher operative morbidity and impacting on long term outcome.

  • Postoperative radiotherapy should be considered for patients in which the meningioma has not been completely resected following surgery or for those in which the meningioma belongs to a more aggressive subtype (WHO grades II or III).

 

 

Some useful references

  • Hashimoto N, Rabo CS, Okita Y, Kinoshita M, Kagawa N, Fujimoto Y, et al. Slower growth of skull base meningiomas compared to non-skull base meningiomas based on volumetric and biological studies. J Neurosurg 116(3): 574-80, 2012.

  • Lee EJ, Park JH, Park ES, Kim JH. “Wait and see” strategies for newly diagnosed intracranial meningiomas based on the risk of future observation failure. World Neurosurg 107:604-11, 2017.

  • Oya S, Kim SH, Sade B, Lee JH. The natural history of intracranial meningiomas. J Neurosurg 114(5):1250-6, 2011.

  • Nakamura M, Roser F, Michel J, Jacobs C, Samii M. The natural history of incidental meningiomas. Neurosurgery 53(1): 62-70, 2003

  • Yano S, Kuratsu J, Kumamoto Brain Tumor Research Group. Indications for surgery in patients with asymptomatic meningiomas based on an extensive experience. J Neurosurg 105:538-543, 2006.

  • Alvernia JE, Dang ND, Sindou MP. Convexity meningiomas: study of recurrence factors with special emphasis on the cleavage plane in a series of 100 consecutive patients. J Neurosurg. 115(3):491-8, 2011.

  • Hasseleid BF, Meling TR, Ronning P, Scheie D, Helseth E. Surgery for convexity meningioma: Simpson grade I resection as the goal. J Neurosurg 117(6):999-1006, 2012.

  • Morokoff AP, Zauberman J, Black PM. Surgery for convexity meningiomas. Neurosurgery 63(3):427-33, 2008.

  • Kaur G, Savegh ET, Larson A, Bloch O, Madden M, Sun MZ, et al. Adjuvant radiotherapy for atypical and malignant meningiomas: a systematic review. Neuro Oncol 16(5):628-36, 2014.