My son (28 years old) has three inoperable meningioma tumors. He completed proton beam therapy at Mayo a year and a half ago. Besides fatigue and a small amount of hair loss, he did very well! He even drove himself to all thirty treatments, 90 minutes each way! At his most recent MRI one month ago, he had no changes in the size of the tumors. His radiation oncologist says this is still a win because the tumors are not growing.
Best of luck with your treatments.