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.
While folks died all the time on the original Star Trek, the main castmembers' demises never lasted much beyond the next commercial break. Tasha, however, changed all that. Suddenly, after her passing on Vagra II at the hands of the evil oil slick Armus, all bets were off on Star Trek. Main characters really could die.