A study of 114 surgically treated patients with intracranial meningiomas was carried out to evaluate factors influencing recurrence. The data of the initial surgery extended over a 24-year period from January, 1956, to December, 1979. The patients ranged in age from 1 1/2 years to 82 years. Seventy-one (62.3%) were females and 43 (37.7%) were males. The surgical procedure was graded according to Simpson's classification from 1 to 5 (Grade 1 = complete excision, Grade 5 = simple decompression). In this series, 33 procedures (28.9%) were Grade 1, 55 (48.2%) were Grade 2, seven (6.1%) were Grade 3, 18 (15.8%) were Grade 4, and one (0.9%) was Grade 5. There were eight (7%) postoperative deaths. Approximately 60% of the tumors were located in the sphenoid wing (23.7%), convexity (21.1%), and parasagittally (14.9%). Histological diagnosis in 96% of the patients was transitional (42.1%), syncytial (34.2%), and fibroblastic (20.2%) meningiomas. Eight (7%) patients received postoperative radiotherapy. There was evidence of recurrence in 22 patients (19.3%). Twenty-one underwent a second surgical procedure. Using survival analysis, it was determined that 80% of the patients were free of recurrence 5 years after the initial surgery, and approximately 50% showed no recurrence 20 years after the initial surgery. Only the grade of the initial surgery had a statistically significant influence on recurrence. Sex of patients, site and histology of the tumor, and postoperative radiotherapy had no statistically significant influence on recurrence. Angioblastic and malignant meningiomas were rare (only four cases), and recurred relatively quickly.

The recurrence of intracranial meningiomas after surgical treatment.

The rates of survival, tumor recurrence, and tumor progression were analyzed in 225 patients with meningioma who underwent surgery as the only treatment modality between 1962 and 1980. Patients were considered to have a recurrence if their studies verified a mass effect in spite of a complete surgical removal, whereas they were defined as having progression if, after a subtotal excision, there was clear radiological documentation of an increase in the size of their tumor. There were 168 females and 57 males (a ratio of 2.9:1), with a peak incidence of tumor occurrence in the fifth (23%), sixth (29%), and seventh (23%) decades of life. Anatomical locations were the convexity (21%), parasagittal area (17%), sphenoid ridge (16%), posterior fossa (14%), parasellar region (12%), olfactory groove (10%), spine (8%), and orbit (2%). The absolute 5-, 10-, and 15-year survival rates were 83%, 77%, and 69%, respectively. Following a total resection, the recurrence-free rate at 5, 10, and 15 years was 93%, 80%, and 68%, respectively, at all sites. In contrast, after a subtotal resection, the progression-free rate was only 63%, 45%, and 9% during the same period (p less than 0.0001). The probability of having a second operation following a total excision after 5, 10, and 15 years was 6%, 15%, and 20%, whereas after a subtotal excision the probability was 25%, 44%, and 84%, respectively (p less than 0.0001). Tumor sites associated with a high percentage of total excisions had a low recurrence/progression rate. For example, 96% of convexity meningiomas were removed in toto, and the recurrence/progression rate at 5 years was only 3%. Parasellar meningiomas, with a 57% total excision rate, had a 5-year probability of recurrence/progression of 19%. Only 28% of sphenoid ridge meningiomas a second resection, the probability of a third operation at 5 and 10 years was 42% and 56%, respectively. There was no difference in the recurrence/progression rates according to the patients' age or sex, or the duration of symptoms. Implications for the potential role of adjunctive medical therapy or radiation therapy for meningiomas are discussed.

Meningioma: analysis of recurrence and progression following neurosurgical resection

Tumors of the nervous system: Incidence and population selectivity

BACKGROUND

Due to the rarity of malignancy in meningiomas, prior studies have been limited to small series. Controversies regarding the definition of malignant meningioma have complicated matters further. Although histologic anaplasia and extracranial metastasis are established criteria, the former is difficult to define and the latter represents a clinical finding. Traditionally, brain invasion has also been accepted, although this has recently been debated. In a prior series, the authors were unable to prove that 23 meningiomas that had invaded the brain were more aggressive than atypical meningiomas.



METHODS

The authors expanded their analysis to include 116 patients diagnosed with “malignant meningioma” due to brain invasion, frank anaplasia (20 mitoses per 10 high-power fields or histology resembling carcinoma, sarcoma, or melanoma), and/or extracranial metastasis. Patients were followed until death or for a median of 3.7 years.



RESULTS

Survival time was highly variable, ranging from 10 days to 24 years. In multivariate analysis, histologic anaplasia (P = 0.0035), subtotal resection (P = 0.0038), 20 mitoses per 10 high-power fields (P = 0.0071), and nuclear atypia (P = 0.0068) were associated with poor survival. Of the 89 cases of meningioma that had invaded the brain, 23% were otherwise benign, 61% were otherwise atypical, and 17% were frankly anaplastic. Those without anaplasia behaved similarly to atypical meningiomas from the authors' prior study. In contrast, anaplastic meningiomas were usually fatal, associated with a median survival of 1.5 years.



CONCLUSIONS

Based on these findings, the authors suggest that brain invasion constitutes an additional criterion for the diagnosis of atypical meningioma (World Health Organization [WHO] Grade II), whereas frank anaplasia indicates high grade (WHO Grade III–IV) malignancy. Cancer 1999;85:2046–56. © 1999 American Cancer Society.

Harvey Cushing

Papers

Meningiomas : their classification, regional behaviour, life history, and surgical end results