When you're an self-absorbed piece of shit whose identity revolves around your ailments and not the merit of your character, anything that even remotely negatively impacts your life is the end of the world because you are the one and only thing you value. Everything is filtered through the thought of, "How can I make this about how pathetic I am for maximum pity?" She specifically chose the phrase "womb cancer" because more directly referring to an inability to have children packs a stronger punch than "uterine cancer".
"Precancerous cells"? It was translated in Amber's brain as, "You're going to get cancer." because she knows better than anyone else that she does not want to change her behavior. Then it turned to "You have cancer." and then it follows "You are going to die." (Because, duh, cancer remission and cancer survivors aren't a thing.)
Amber reflects a lot of the behavior of people in my life I - probably similarly to some of you - cut out. They all do this: Behave badly, do bad things, treat their bodies badly, think they get away with it in the moment because they hide the evidence from others and themselves or outright deny reality, and when the consequences rear their heads, they either lash out angrily or beg incessantly for pity as if they were not responsible. They hound and devour honest people because nothing in life is more valuable than hearing the words, "I feel so bad for you." Their only life goal is to be the last person to say that to themselves on their death bed.