My father was diagnosed with GBM Grade IV in August and has completed his resection and first round of radiation / Temodar. He had a good AGT test and Duke put him on Temodar for 2 more months. I understand that Duke generally likes to rotate chemo treatments because they believe that the Cancer will eventually become resistant to the Temodar if they stay on it too long. But how long is too long? A doctor at NIH has recommended we stay on Temodar for 6 months which goes against Duke's resistance regimen. Does anyone have information on how long someone should stay on Temodar for or anything to back the Duke theory that the body will become resistent?