Selfish? Maybe. I've been through this with members of my family. Some rather quickly, some not so quickly. For each of them it was FEAR: fear of what tests would reveal, fear of what a Dr. would say, fear of losing a breast (or maybe both) to a mastectomy, fear of how their husband would look at them, fear there would not still be a woman with only one or no breasts. Fear of death was further down the road. I cannot comment on OP's sister-in-law's thought process, but from my experience fear was a factor. I' ll pray.
