We identified 1003 patients with meningiomas who had received treatment at VCU Medical Center from 2005–2015. 76.47% were females, 61.52% were Caucasian, and participant’s mean ± SD age was 67.55 ± 15.50 years. Of the 1003 patients, 26 patients met the inclusion criteria, 11 were excluded, leaving a final sample cohort of 15 patients with radiation-induced meningiomas.
Of the RIM patients, 66.67% were female and 33.33% male; 33.33% were African-American and 66.67% were Caucasian. The average age at diagnosis of RIM was 43.27 ± 15.06 years. The average latency period from radiation treatment to tumor diagnosis was 356.27 ± 116.96 months. The average number of treatments was 2.47 ± 1.19, and the average initiating radiation dose was 44.28 ± 14.68 Gy. The prevalence of RIMs within our cohort of all meningiomas was 1.5%.
The most common reason for prior radiation was ALL, followed by medulloblastoma. The brain tumor group was the most common reason for prior radiation in our database. Prior radiation among females was most often for hematologic malignancy and brain tumors, while for males it was brain tumors.
We found that there was a significant difference between latency period by ethnicity (Table 1) with a mean latency time of 258.3 months in the African-American population and 405.2 months for the Caucasian population (p = 0.003). There was a significant difference between the number of lesions by gender, with the mean for males of 1.4 and females 2.8 (p = 0.046) in Table 1. Furthermore, the mean latency time in males (283.4 months) was shorter compared to females (392.7 months), but this difference was not statistically significant (p = 0.163). Male gender was also associated with higher histology, 75% of males were WHO Grade II compared with 42.86% of females were WHO Grade II, although this difference did not attain statistical significance (p = 0.55).
Table 1
RIM characteristics (mean and standard deviation) stratified by sex, race, and histology
| Sex | Race | Histology |
Male | Female | Caucasian | African American | WHO I | WHO II |
Number of Lesions | 2.8 ± 0.89 | 1.2 ± 1.40* | 2.4 ± 1.51 | 2.2 ± 1.30 | 2.2 ± 1.30 | 2.67 ± 1.63 |
Latency, Months | 283.4 ± 117.5 | 392.7 ± 103.5 | 405.2 ± 100.5 | 258.4 ± 84.68** | 386.6 ± 58.14 | 374.7 ± 152.0 |
Age at Diagnosis, Years | 49.2 ± 19.12 | 40.3 ± 12.68 | 41.9 ± 12.39 | 46 ± 20.84 | 40.4 ± 7.80 | 44.67 ± 20.31 |
*p = 0.046; **p = 0.003; All other p-values > 0.05. |
WHO: World Health Organization |
Of the 15 patients, 3 were observed clinically, 1 patient received surgery only, 7 received surgery and radiation, 3 received surgery and medical treatment, and 1 patient received surgery, radiation, and medical treatment. Of note, the radiation treatment category included patients who had fractionated radiation treatments and radiosurgery. Only two patients received radiosurgery for their RIM.
Finally, of the RIMs with characterized histology within a pathology report, 6 were identified as WHO grade II, and 5 were WHO grade I. Of note histology grade did not have significant differences in latency, the number of lesions, and age at diagnosis.
We defined “progression” as the regrowth of a previously treated lesion. The mean overall progression-free survival was 81.4 ± 8.7 months (Fig. 3a). The 10-year progression-free survival rate was 50%. When the patient cohort is stratified by histology, the mean progression-free survival for grade 1 tumors was 85.4 ± 14.7 months, while for grade 2 tumors the mean progression-free survival was 49.5 ± 0.11 months (Fig. 3b). The 10-year progression-free survival rates for both groups were 50%. The 5-year progression-free survival rate for grade 2 meningiomas was 50%, while the 5-year progression-free survival rate for grade 1 meningiomas was 75%. Despite this difference at 5 years, the 10-year progression-free survival rates for both groups were 50%. The mean progression-free survival for patients who received radiation as a treatment was 44.3 ± 2.3 months (Fig. 5). At 5 and 10-years, 58% of these patients were progression-free.
We defined “recurrence” as the growth of a new lesion in these patients. The mean overall recurrence-free survival was 31.2 ± 6.4 months (Fig. 4). The 10-year recurrence-free survival rate was 27%.