I am replying with a seemingly same experience.
To state the obvious, you have (2) issues in play, the meningioma and the edema.
Be equally concerned about the edema. It is my understanding that steroids prescribed for the edema are only 70% effective. I would find out if the steroids will effectively treat your edema before you treat the meningioma.
Steroids show effectiveness in only few weeks of treatment, so you will know pretty quickly. GET a neurosurgeon opinion.