Study: Vaccine Protects Against Anal Cancer

A new study shows that a vaccine already in use to protect women against the human papilloma virus (HPV), which can cause cervical and other forms of soft tissue cancer, can also be effective at warding off anal cancer.

"Men who were vaccinated against human papillomavirus developed 75 percent fewer anal lesions that lead to cancer than their counterparts who were given a placebo," an Oct. 27 APF story reported.

The study showing the results was published in the New England Journal of Medicine, the article said. The day before the study's publication, the Centers for Disease Control and Prevention (CDC) advised that boys as well as girls should be given inoculations against HPV.

Up to 80 percent of adults will contract the virus at some point, it's thought, but most people do not develop symptoms. The virus can lead to genital warts. Some, however, suffer cancer after infection. The cancer can be cervical, or affect the soft tissues of the neck, throat, and mouth. The virus can be spread through oral sex as well as vagina sex.

But there's another risk factor as well: Anal cancer. As with cervical and neck cancers, precancerous anal lesions can result from exposure to HPV, and those lesions can later become cancerous.

Some parents fear that inoculating their daughters is tantamount to giving them permission to be sexually promiscuous. In the case of sons, some parents may feel that the inoculation confers a blessing for the child to grow up gay.

" 'Why are you vaccinating my son against anal cancer? He's not gay! He's not ever going to be gay!' " Georgetown University School of Medicine's Ranit Mishori told the Associated Press, which published a story on the CDC's recommendation on Oct. 25. "I can see that will come up."

But medical experts say that practical health precautions outweigh squeamishness, and also note that it's not only a matter of protecting males against getting cancer. It's also more likely that unvaccinated straight men will spread the virus to women, who are also at an elevated risk of developing heart disease after exposure to the virus, according to recent research.

The new study involved just over 600 young gay men, aged 16-26, who had had between one and five sexual encounters at the time they entered the study. Some of the young men were injected with Gardasil, a vaccine that protects against HPV and is manufactured by Merck, which funded the study.

But others received a placebo. After three years, the men who had received Gardasil and been exposed to one or more of the viral strains that Gardasil is designed to protect against showed a 54 percent lower incidence of anal lesions and HPV infection than the men who had gotten the placebo, the AFP story reported.

The men who had not been infected with HPV showed a 75 percent lower incidence of anal lesions.

"Based on these data, the vaccine works well to prevent HPV infection and precancerous anal disease, and will likely prevent anal cancer in men," the study's lead author, Joel Palefsky, said. "The ideal time to begin vaccination would be before initiation of sexual activity, but vaccination may also be useful after initiation of sexual activity."

"HPV vaccination, while most effective when given before the onset of sexual activity, reduces recurrence rates of anogenital warts and precancerous lesions in patients who have had clinically evident disease caused by preexisting infection with one or more HPV subtypes," agreed Mount Sinai School of Medicine's Michael Gaisa, who was not one of the study's authors,

The APF reported that around 6,000 people are diagnosed with anal cancer every year in the U.S. Around 800 people die of the disease annually. By contrast, HPV seems to account for about 13,000 cases of cervical cancer per year in the U.S. About 4,300 women die each year of cervical cancer.