@thomhorowitz, here is a list of discussions where member have talked about the Optune device https://connect.mayoclinic.org/group/brain-tumor-support-group/?search=optune&index=discussions

My husband, David, has been on the Optune device for six days. So far so good. I am the primary care giver and have changed the arays twice (every 3 days ). It was not hard to do... a little nerve racking the first time. We found the training and support good and understand anything medical (i.e. skin irritation, headache, or other side effects) must be referred to our prescribing physician. No side effects thus far. The device is a lifestyle change for sure, but David has continued his morning runs with a backpack on. We are going to try practicing golf tomorrow to see if possible. He is 75 years old and used to an active life. Trying Optune is worth it for us if it provides an extension of life and maintains quality. Understandable that it is not for everyone.