Annabelle Gurwitch is an actress and the author of six memoirs. Her latest is “The End of My Life Is Killing Me,” from which this essay is adapted. “Are you sure you have cancer? You don’t have the cancer look.” After my out-of-the-blue diagnosis of stage 4 lung cancer, I got stupefying comments of this sort, or the more colloquial “You don’t look cancery,” from even my most well-intentioned friends. They were mistaking the effects of some treatments for symptoms of the disease itself.