Cervical cancer is interesting, because we actually do know what leads to it. Almost all cases of cervical cancer are caused by the human papillomavirus or HPV. HPV is a sexually transmitted disease that many women contract. Most of them are able to fight the virus off just with their own immune systems. But for a small percentage of women the virus remains in the cervix and eventually leads to cellular changes that cause cells to become precancerous and abnormal.
The best way to prevent HPV is to limit your sexual partners although condoms are now believed to offer some measure of protection.