She's young enough to have been offered the Gardasil vaccine in her teens at the OB/GYN. It is known to prevent types of HPV including genital warts and strains that are known to cause uterine cancer that you can get later in life while sexually active. 80 percent of all uterine cancers are caused by the types of HPV to which the vaccine would provide immunity. The only issue is it's a bit of a pain in the ass, you have to go back to the doctor one or two times (can't remember exactly) after the initial visit as it's given in separate shots over several months. They're totally painless and go in your arm. I could totally see Amber being too lazy to get the full rounds of this life-saving shot. It would have been covered via her parents' insurance until age 26 or by medicaid if her parents didn't have coverage through work, although the latest they recommend you get it is 22 I think.
So tl;dr there's a significant chance she got uterine cancer from unprotected sex with some dude with HPV/genital warts and refusing to get a slightly inconvenient round of cheap/free vaccinations.
More info on the vaccination and what it prevents
here.