Background: Clinical equipoise still exists in the management of WHO grade II meningiomas following
gross total resection (GTR). Specifically, whether to radiate upfront after resection
or at initial recurrence. This study aims to compare strategy failure-free survival
(SFFS) between two treatment strategies after GTR: adjuvant radiation versus observation
with salvage radiation after initial recurrence.
Methods: A retrospective review of patients who underwent GTR of newly diagnosed WHO grade
II meningiomas at our institution between 1996 and 2019 was performed. Treatment failure
was defined as failure of first radiation. To assess the association between treatment
strategy and SFFS while accounting for potential confounders, a multivariable Cox
regression analysis adjusted for the propensity score (PS) and inverse probability
of treatment weighted (IPTW) Cox regression analysis were performed.
Results: There were 161 patients who underwent GTR as initial treatment and were included
in this study. Of these, 39 patients received adjuvant fractionated external beam
radiation therapy (fEBRT) and 121 patients were observed. Failure of adjuvant radiation
occurred in 8 (20.5%) patients. Out of 37 (30.6%) patients who were observed and developed
recurrence, 32 (26.4%) were treated with salvage radiation (IMRT or SRS) and 5 (4.1%)
were treated with salvage surgery. There were 8 (25.0%) patients who experienced failure
of salvage radiation.
The 3- and 5-year SFFS was 86.1 and 59.2% for the adjuvant radiation strategy versus
97.7 and 90.3% for the observation with salvage radiation treatment strategy, respectively.
The observation with salvage radiation treatment strategy achieved a significantly
longer SFFS than the adjuvant radiation cohort (p = 0.0005). PS and IPTW Cox regression models demonstrated that the observation with
salvage radiation treatment strategy was significantly associated with prolonged SFFS
(HR = 0.21; 95% CI: 0.07–0.70 and HR = 0.21; 95% CI: 0.07–0.58, respectively).
Conclusion: SFFS was significantly greater in patients treated with observation followed by salvage
radiation as compared with adjuvant radiation after GTR of newly diagnosed WHO grade
II meningiomas. A treatment strategy of observation with salvage radiation for initial
recurrence may be advantageous over adjuvant radiation by reserving radiation for
recurrence.
Fig. 1 Flow diagram of patients utilizing different strategies after GTR of a newly diagnosed
WHO grade II meningioma. The start of the arrow indicates index time and the end of
the arrow denotes event time for progression-free survival. *Salvage surgery excluded
from final analysis. GTR, gross total resection; IMRT, intensity modulated radiotherapy;
SRS, stereotactic radiosurgery.
Fig. 2 Progression-free survival in patients undergoing GTR, stratified by adjuvant radiation
versus (A) observation with salvage radiation, (B) observation only, (C) salvage radiation only.
