To treat a pituitary tumor with radiation, doctors may use a variety of techniques depending on the size and location of the tumor. Conventional radiation covers a wide area in and around the tumor and is usually given daily for several weeks.
In the show, Stannis Baratheon dies under the sword of Jamie Lannister, wielded by a woman to fulfill a promise to Catelyn Stark, to avenge the death of Renly Baratheon. You can state he died of internal complications.
Well, not we, them. The armies of two extremely formidable and determined men, Stannis Baratheon and Roose Bolton, facing off while a ridiculous winter storm rages. This three part series goes beyond a single battle, however. Even our love of detail is not enough to make 3 episodes out of that.