The same vaccine that protects women from cervical cancer also prevents an oral infection that sometimes leads to throat cancer in both sexes, a new study has found. And the throat cancer is actually much more common in men than women.
The vaccine has been controversial in the U.S. The U.S. Centers for Disease Control and Prevention recommend boys and girls get a human papillomavirus vaccine around age 11 or 12. However, some parents oppose the recommendation because they believe offering the vaccine gives their kids the message that sexual activity is okay. Others seem to think their kids won’t need it.
The new study found that among 2,910 women who got Cervarix, an HPV vaccine made by GlaxoSmithKline, only one got an oral HPV infection after four years. Among the 2,924 women who didn’t get Cervarix, 15 had an oral HPV infection. That makes the vaccine 93 percent effective against oral HPV infection, the study scientists wrote in a paper they published yesterday in the journal PLOS ONE.
This is the first time anybody has studied whether an HPV vaccine protects against oral as well as genital infections. The results could make HPV vaccines more popular among men and boys—or rather, the parents of boys, who decide whether to vaccinate them. While cervical cancer affects only women, both sexes can get HPV infections that lead to genital warts, anal cancers and oral and throat cancers. Men are four times more likely to get oropharyngeal cancers—a cancer of the back of the throat—than women.
The study didn’t include any men, but previous studies have found that HPV vaccines are equally effective against infections in men and women.
Cervarix protects against two strains of the human papillomavirus, HPV16 and HPV18. HPV16 shows up in 90 percent of HPV infections. It also causes a subset of oropharyngeal cancers. In the past, drinking and smoking caused the majority of such throat cancers, but recently, doctors have seen increasing numbers of HPV-caused oropharyngeal cancers, especially among young adults in developed countries. Researchers now think viruses cause 30 percent of oropharyngeal cancers worldwide.
Just last month, actor Michael Douglas told the U.K.’s The Guardian that his throat cancer was caused by an infection from performing oral sex on a woman. (A doctor The Guardian talked with, who hadn’t treated Douglas, seemed to think it’s more likely Douglas’ cancer came from a combination of smoking, drinking and infection.) Douglas said he has been clear of the cancer for more than two years now.
An estimated 14 million Americans get infected by HPV every year. Although most won’t see any symptoms, the virus can cause genital warts, cervical cancer and other cancers.
The study was performed in Costa Rica, with funding from the U.S.’ National Cancer Institute. The study scientists came from institutes in Europe, the U.S. and Costa Rica. GlaxoSmithKline donated the vaccine for the study.