Runaways: "why are these girls here?"

Most runaways are girls. Why are these girls here? They may be here because they have been victimized or abused. Most girls who have been victimized fear the shame that will be brought upon them and their families, so they keep it a secret or runaway. Many sad stories have been told about girls running away because they were abused and raped. So what can we do to help them? How can we help them? How can we stop the abuse and rapes?