Source: www.buffalonews.com
Author: Henry L. Davis

Parents who face the dilemma of whether to protect their young daughters with a vaccine aimed at a sexually transmitted infection that causes cervical cancer now face a new question: Should they do the same for their sons?

As evidence mounts of a rising number of other cancers linked to the human papillomavirus, or HPV, a debate has intensified over whether to give the vaccine to males.

Advocates say vaccinating boys and men can prevent them from passing on the virus to their sexual partners.

Critics still question the long-term safety and effectiveness of Merck & Co.’s Gardasil, despite studies indicating that its risks and lasting power are within the range of other vaccines.

But a newer wrinkle in the debate is the discovery in recent years that oral HPV infections — most likely acquired from oral sex with multiple partners—significantly increase the risk of head and neck cancers.

The rate of oral cancers is rising so steadily, especially in men, that, if the trend continues, there may be more oral cancers in the United States caused by HPV in 10 years than by tobacco or alcohol, a major study concluded last year.

“We should be investing our care and dollars in preventing HPV infection instead of treating the cancers,” said Dr. Thom Loree of Roswell Park Cancer Institute.

Physicians at the cancer center have begun publicly touting the benefits of the vaccine on males after seeing an increase in the number of throat cancers they treat annually over the last decade. HPV was associated with about 55 percent of the tumors.

Although many researchers believe Gardasil can protect against oral and other cancers linked to HPV infections, including rarer cancers of the penis and anus, studies that might provide compelling evidence have yet to be completed.

HPV, a family of more than 100 viruses, is the most common sexually transmitted infection. An estimated 20 million Americans are infected, and at least half of all men and women acquire a genital HPV infection at some point in their lives, according to the Centers for Disease Control and Prevention.

In most cases, there are no symptoms and the infection goes away. But some types of HPV cause genital warts and cancers.

HPV-associated cancers occur most often in the cervix, with about 10,000 cases and 3,700 deaths each year. There are about 1,000 deaths each year among U. S. men from HPV-linked cancers.

The Food and Drug Administration approved Gardasil in 2006 for women ages 9 to 26 to prevent cervical, vulvar and vaginal cancers caused by HPV. The federal Advisory Committee on Immunization Practices recommends that all girls be vaccinated at age 11 or 12 and those ages 13 to 26 be given “catch up” vaccinations.

Merck has applied to the FDA to use the vaccine on boys and men ages 9 to 26. The official indication would be for prevention of genital warts and other lesions, although pediatricians would be free to discuss with parents the potential for protection against cancers.

The immunization advisory committee met in June to discuss vaccination of males, including whether it is cost-effective, and plans to vote on the matter in the fall.

Gardasil protects against four strains of HPV, including two that account for 70 percent of cervical cancers and two others that account for nearly all cases of genital warts.

Experts say restricting the vaccine to girls makes it less effective at reducing infections.

“There are many direct and indirect benefits to vaccinating men for HPV, although it’s important that we look at whether it’s cost-effective,” said Dr. Gale Burstein, medical director of epidemiology and surveillance and STD control for Erie County.

Burstein, a pediatrician who specializes in adolescent medicine, also consults for Merck and GlaxoSmithKline, which has applied to the FDA to market its competing Cervarix vaccine in the U. S.

Another Buffalo-area physician, Dr. Michael Terranova, chairman of the Buffalo Area Pediatric Society, also sees benefits in immunizing boys.

“It’s a good vaccine,” he said. “You would eliminate thousands of cases of genital warts and cancers.”

Critics, though, point out that unlike mandated vaccines, only about 25 percent of teenage girls get Gardasil and that vaccinated women must continue regular Pap tests to detect precancerous lesions because Gardasil does not protect against other strains of HPV that cause cervical cancer.

This, in turn, raises doubts about the vaccine’s cost-effectiveness, particularly when a Pap test ranges from $6 to $16 and the three recommended doses for Gardasil cost $375.

“This is a very expensive vaccine with limited effectiveness,” said Diana Zuckerman, president of the National Research Center for Women and Families. “For men, we know that the vaccine will prevent genital warts. How much are we willing to pay to prevent genital warts?”

Critics note that most cases of HPV clear on their own and raise doubts about the lasting power of the vaccine. They also question its safety.

Merck counters that research shows immunity lasts at least 8.5 years, and that proof of enduring protection has not been a requirement of other vaccines.

As of May 1, more than 24 million doses of Gardasil were distributed in the United States. There were 13,758 reports of adverse events, with 7 percent considered serious, according to the government’s Vaccine Adverse Event Reporting System.

Although studies have yet to show that Gardasil prevents oral cancers, scientists remain optimistic that it can.

“No one can make a claim that it will do anything for other cancers. But there is no reason to believe it won’t work,” said Dr. Maura Gillison, a leading expert on HPV and oral cancers.

Researchers attribute the rise in HPV-associated cancers, especially oral cancers among younger white men, largely to changes in sexual attitudes.

The greatest risk factor for developing a cancer from an HPV infection is multiple sexual partners, Gillison said.

All of which may add a challenging twist for doctors if the vaccine is approved for males.

“Talking to boys or their parents about protecting girls from cancer is not going to get them to take the vaccine. They have to see a direct benefit,” said Dr. Cynthia Rand, who has studied public perceptions toward HPV vaccination.