Natural History of Meningiomas: Review with Meta-analyses

Abstract

Observation has been a mainstay in asymptomatic meningiomas, but it may increase the risk associated with treatment due to tumor enlargement and the aging of patients. Understanding the natural course of meningiomas is important to provide appropriate treatment. The majority of previous studies investigated factors related to their growth, but failed to demonstrate their relationship with symptomatic progression (sympP) because of its rarity. We reviewed and meta-analyzed 27 studies that investigated natural courses in asymptomatic or untreated meningiomas to find clinico-radiological factors predictive of radiological progression (radioP), growth speed, and sympP. In results of time-growth analysis, twothirds of meningiomas showed radioP defined by a volume criterion and the rate approached a plateau at 4-5 years. In growth curve analyses, about half of incidental meningiomas presented decelerating or no growth, while less than one-quarter of them grew exponentially. RadioP, growth speed [annual volume change (AVC) or relative growth rate], and sympP each had different factors related to them. Younger age, non-calcification, and high intensity on T2-weighted image were related to radioP and rapid growth speed, but not to sympP. Tumors in males and those of larger size were likely to be symptomatic in the meta-analysis. AVC (≥2.1 cm 3 /year) was the strongest indicator of sympP. Apart from perifocal edema, radiological features at up-front imaging may not be useful for predicting sympP. This may be due to dynamic changes of those radiological markers in the long term. Quantified tumor size and growth speed, especially AVC, are important markers for deciding on treatment.

Initial Gamma Knife Radiosurgery for Large or Documented Growth Asymptomatic Meningiomas: Long-Term Results From a 27-Year Experience

“…They also found initial tumor diameter of >2.5 and 3 cm went on to develop new or worsened symptoms 17% of the time. In a recent metaanalyses, Nakasu et al (12) also found large initial maximum diameter were significantly associated with symptomatic progression. As a high risk of symptom progression in large tumors, these patients may gain benefit from earlier treatment before the occurrence of symptoms.…”

“…Recent European Association of Neuro-Oncology guidelines indicates that surgery is the first option when treatment is indicated in meningioma of any WHO grade (18). However, surgical resection is an invasive treatment, depends on tumor location and can cause significant morbidity (12). In the study of Naslund et al (19), 30-day complication rate was significantly higher among the asymptomatic cases.…”

“…In a population-based analysis, the use of primary observation increased for smaller tumors (<2 cm), relative to surgery and radiation (11). In a recent meta-analysis, those tumors with larger size were likely to be symptomatic (12). Therefore, treatment should be recommended for large tumors, symptomatic tumors and those documented growth.…”

How much tumor volume is responsible for development of clinical symptoms in patients with convexity, parasagittal, and falx meningiomas?

“…Meningiomas are benign neoplasms that can exhibit a variety of growth patterns [8,9] and, eventually, 67%-75% of them enlarge [6,9,10]. In one study, tumor volume was statistically signi cantly related to the appearance of clinical symptoms [5].…”

Malignant transformation of WHO grade I meningiomas after surgery or radiosurgery: systematic review and meta-analysis of observational studies

“…Meningiomas are usually indolent tumors that often remain asymptomatic. 1 Even when symptomatic, approximately 80% of meningiomas are categorized as WHO grade I and slow-growing tumors that exhibit decelerated growth during enlargement. 2 However, even benign meningiomas can recur after total removal, and some of these lesions are known to behave more malignantly.…”