I would argue we already know the solution, and it isn't legalization.

From my source above "The research team identified the contrasting domestic policies on prostitution of Sweden, Germany and Denmark as significant examples that were representative of their conclusions. In 1999 Sweden passed legislation that criminalized the buying of sex, and decriminalized the selling of sex. The principle behind this legislation is clearly stated in the government’s literature on the law: “In Sweden prostitution is regarded as an aspect of male violence against women and children. It is officially acknowledged as a form of exploitation of women and children and constitutes a significant social problem… gender equality will remain unattainable so long as men buy, sell and exploit women and children by prostituting them.”

The legislation virtually wiped out prostitution and sex trafficking in Sweden. The Swedish government estimates that since 1999 only 200 to 400 women and girls have been annually trafficked into Sweden for prostitution, while in neighboring Finland the number is reported to be 15,000 to 17,000."