Hello, and welcome to the forum that no-one ever wants to join.  Your post is a little bit confusing.  You say that his daughter says that he has possibly 2 months of life left, and then you say that he has been diagnosed today with a prognosis of maybe 18 months of life.  It sounds like your cousin has been told that he has terminal throat cancer and that if he has treatment, he MIGHT get an extra 2 months of life.  The treatment will undoubtedly be gruelling, and for a couple of extra months of life, is it worth going through all that suffering?  Your cousin doesn't seem to think so, and neither does his daughter, who, I believe, is acting NOT from a place of selfishness, but from a place of Love...........your cousin's daughter doesn't want to see her Dad suffer so much for so little in return.  In other words, she has put her own needs to one side and she is putting the needs of her Dad ABOVE her own.  She wants what is best for HIM, and not what is best for her.  Frankly, there is no higher form of Love than that.  You ask if you are being selfish in wanting your cousin to carry on with treatment, even though it won't do much good, and the honest answer to that question is yes, you are being a little bit selfish, even though I realise that you love your cousin deeply and you don't want to lose him.  At the end of the day, the choice must be his and his alone.  Don't make it harder for him than it already is........support him whatever he decides to do.