Why do doctors recommend HPV vaccines for boys?

Prevent carriers. Males can get penile cancer 1% of the time from hpv. 50% of head and neck cancers are now due to hpv. Anal cancers are about 25% related to hpv and of course they can spread it to girls who have a 30% chance of getting cancer from hpv. To stop this disease we need to vaccinate everyone.
Cancer prevention. Hpv vaccine for males will diminish the chances of these males from contracting hpv and thus from subsequently transmitting hpv to their partner/s. It also diminishes the chances of hpv associated penile carcinoma, and virtually eliminates the risk of condylomata.
Prevent cancer. Hpv is a sexually transmitted virus. So women who get hpv from their partners are at higher risk for cervical cancer. In addition, men can get penile cancer from hpv if they are immune suppressed. Finally, both men and women can get genital warts which the vaccine can help prevent. Hpv vaccine covers the 4 most common types of the virus including two that cause warts and two that cause cancer.