Earlier in my life and thinking, I would have understood and framed arguments against euthanasia in terms of the dignity and value of each human person, the objective moral law against killing, and God's ownership of human life.
Such arguments are true and valid and necessary to make.
But the problem is they're only convincing to people who believe in God and/or moral absolutes, while the default mode of ethical thinking in our society is relativistic and inclined toward radical autonomy, e.g.: "If he wants it, then it's right for him."
A very large portion of our society find reasoning like cancer-stricken Kevin Drum's persuasive.
I have no interest in trying to tell other people what to do if they find themselves close to death, but my choice has always been clear: I don't want to die in pain—or drugged into a stupor by pain meds—all while connected to tubes and respirators in a hospital room. When the end is near, I want to take my own life.
Most people find such reasoning persuasive not because they love death, but because they feel compassion; they, too, dread suffering; they, too, don't want to be a burden to their loved ones, and they respect personal autonomy.
Given all that, I think we need to do more to develop arguments like this one, which Daniel Payne wrote in direct response to Drum. It's true; it's deeply personalistic, and it's closer to modern experience and modern sensibilities than objectivist arguments.
If his cancer should return, however, I pray he does not take the easier way out. I pray he gives his wife and his loved ones a final, priceless, and irreplaceable gift, a gift of himself that only he can give: the gift of needing their love, their attention, and their full and unconditional care in the twilight moments of his precious life.