My girlfriend wants to save herself for marriage, the doctor just told her she has cervical cancer, and she says she never had sex with any man before, except when she was rape at 8. Should i belive her when she said she did not have intercourse? why?

if she says she hasnt then u should take her at her word. just because she has cervical cancer doesnt mean she got it from sex!

Why should you believe her?

Well, on the most basic level because she's the one you're contemplating living the REST of your life with, right?
So if you can't trust her over this, then what on earth makes you think you could trust her on something else.
If she said that she's been trying to be chaste, then you need to either believe her or not.
And if you don't, then you have no business being further involved in her life...especially if she's going through such a horrible thing right now!

As for cervical cancer, roughly only 70% of all cases are caused by HPV infection via sexual transmission...And OH YEAH.. she was RAPED when she was EIGHT YEARS OLD. Don't you suppose transmission might have happened during the RAPE??????

The other 30% have NO CAUSE.
Therefore it may be caused because she's genetically presdisposed to have it, or she got too many x-rays, or because it was Tuesday and she had the misfortune of eating an almond cookie at noon that day.
So do NOT go jumping the gun on this one.

The bottom line is this: She needs a LOT less sh!t from you right now.
As a cervical cancer survivor myself, I can tell you first hand that she needs support, NOT ACCUSATIONS from a narrow-minded jerk.

Either you help or get out.