Hi @peque, welcome to Connect.
This short video from Dr. Baird at the Cancer Treatments Centers of America helps answer your question.
http://www.cancercenter.com/community/questions-and-answers/brain-and-spinal-cancer/can-a-meningioma-become-cancerous/
"Dr. Baird explains meningioma as a benign brain tumor or mass that grows abnormally in the brain. He says the vast majority of meningioma tumors are benign and will not develop cancerous characteristics. Dr. Baird does caution that even though meningioma tumors are typically benign, they can still cause a number of problems because of their location in the brain."

Peque, I'd also like to introduce you to other members on Connect who are living with meningiomas. Please meet @pegorr @barbarabx @ees1 @nancye3 @irishel @lindajean @07ram and others on these discussions:

– Multiple meningioma brain tumors https://connect.mayoclinic.org/discussion/brain-tumors/
- Multiple Meningiomas https://connect.mayoclinic.org/discussion/multiple-meningiomas/
- Meningioma - I'm scared to watch and wait https://connect.mayoclinic.org/discussion/have-had-a-mri-that-revealed-a-large-structure-that-is-presumed/

In these discussion you'll see that several members have followed the "watch and wait" treatment. It's not easy to do. What questions would you like to ask the other members who have been there?