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.
Melisandre Could Bring Him Back from the Dead This is one of the more popular theories. Now that Stannis is (presumably) dead, Melisandre is in search of a new messiah to champion, and sheâs been eyeballing Jon Snow all season.