For those rare patients now out 5 years post GBM treatment and continuous Optune, is there a point one would stop Optune?

I haven’t seen any data from Optune on these very long term survivors. They have released some subset data that patients who used the device 90% of the time or greater had a 29% chance of being alive at 5 years which is pretty remarkable. Certainly think there are diminishing returns beyond 5 years....