An interview in The Guardian with Michael Douglas raised questions about HPV — and here are some answers.
Michael Douglas discussed his battle with throat cancer in an interview with The Guardian newspaper, in which doctors raised the point that some throat cancers can be caused by a sexually transmitted virus, HPV, related to cervical cancer.
But Douglas’ spokesperson has rebutted the newspaper’s headline saying that oral sex caused his cancer. The spokesperson said that the article simply included discussion of oral sex as a suspected cause of certain oral cancers.
USA TODAY asked cancer experts to explain HPV’s role in oral cancer and other diseases.
Q. What causes oral cancers — those of the tongue, tonsils and back of the throat?
A. Both smoking and HPV, the human papillomavirus, are major causes of oral cancer.
Douglas, 68, had previously blamed his cancer — detected at stage 4, the most advanced kind — on years of smoking and drinking. And while tobacco has long been a leading cause of head and neck cancers, HPV now causes far more cases, says Lori Wirth, director of head and neck oncology at Massachusetts General Hospital.
Q. Why are doctors concerned about HPV-related cancer?
A. HPV causes cancer of the cervix, vagina, vulva, anus, penis and head and neck. It also causes genital warts.
Rates of HPV-related cancers have risen dramatically in recent years, even as lower smoking rates have reduced the incidence of many other cancers. In an interview with USA TODAY earlier this year, the American Cancer Society’s Otis Brawley called it “one of the epidemics of the 21st century.”
If trends continue, oral cancers will overtake cervical cancers as the leading cause of HPV-related tumors by 2020, according to the January report.
Q. How fast are HPV-related cancers growing?
A. The proportion of HPV-related oral tumors has grown from 16% of all oral cancers in 1984 to 1989, to 72% of these tumors from 2000 to 2004, according to a January report from the American Cancer Society and Centers for Disease Control and Prevention.
Q. How common is oral HPV infection?
A. More than 10% of men and 3.6% of women have a current oral HPV infection, according to a study of Americans ages 14 to 69 published last year in the Journal of the American Medical Association.
Q. Does everyone who is infected get cancer?
A. In an estimated 85% of cases, a person’s immune system gets rid of the infection, just as it would eventually overcome a cold virus, says Eric Moore, an associate professor of otolaryngology at the Mayo Clinic in Minnesota. The immune system knocks out most HPV infections on the cervix, as well, before they cause harm.
While there are dozens of types of HPV, only a few cause cancer. HPV 16 and HPV 18 cause about 70% of cervical cancers. For oral cancer, the most dangerous subtype is HPV16.
In a fraction of cases, however, HPV infection can persist for years, increasing the risk of cancer, Moore says.
Q. How common is oral cancer?
A. About 7,100 people develop HPV-related oral cancers, according to the Centers for Disease Control and Prevention. HPV, the human papillomavirus, also causes cancers of the cervix, vagina, vulva, anus and penis.
Q. Are spouses at risk, as well?
A. Probably not.
Because men can transmit HPV to their sexual partners, increasing a woman’s risk of cervical cancer, many spouses of those with oral cancer worry that they will also develop an oral cancer, too, Wirth says.
“It’s a really significant emotional and psychological burden,” Wirth says.
A new study, presented Saturday at the annual meeting of the American Society of Clinical Oncology, should reassure spouses, Wirth says.
The study, led by Gypsyamber D’Souza of the Johns Hopkins Bloomberg School of Public Health in Baltimore, found that 65% of men with HPV-related oral cancer had an active HPV infection.
But only 5% of female partners of men with oral cancer had an active HPV infection. That suggests these women are not at higher risk for oral cancer, D’Souza says. About 30% of male partners of men with oral cancer had active HPV infections, putting them at higher risk.
The CDC recommends that boys be vaccinated against HPV at age 11 or 12, in order to protect their future partners from cervical cancer.
Q. Is oral HPV infection more common in men than women?
A. Yes. D’Souza notes that, for reasons doctors don’t fully understand, oral HPV infections are much more common among men than women.
Studies suggest that most women are infected with HPV by one of their first sexual partners. So D’Souza says it’s possible that a woman’s immune system may mount a vigorous response against the virus, inoculating her against further infections.
Q. What’s the prognosis for oral cancer?
A. Fortunately, these cancers grow slowly and take a long time to spread to other organs, Moore says.
HPV-related oral cancers are actually more treatable than ones caused by smoking, Moore says. Although treatment can be extremely hard on patients, requiring months of surgery, radiation and chemotherapy, around 90% of nonsmokers with HPV-related oral cancers are cured. Cure rates are lower for smokers; about 70% of smokers with HPV-related oral cancer are cured. For those with smoking-related oral cancer, about 55% to 60% are cured, Moore says.
Q. Can doctors detect oral cancers early?
A. No, doctors have no screening exams for oral cancer.
Doctors can look at the base of the tongue only with scopes inserted through the mouth or nose, which are quite uncomfortable, Wirth says.
In contrast, cervical cancers can be easily seen with a standard pelvic exam, Wirth says. Cervical cancer progresses through predictable precancerous phases, allowing doctors to study how it develops, and even prevent cancer by detecting and removing these lesions early.
In other interviews, Douglas has been quoted as saying that it took doctors a long time to diagnose the source of discomfort in his throat.
Q. How does HPV go from a virus to cancer?
A. Doctors know relatively little about how HPV-related oral cancers develop, or how long it takes for an infection to cause a tumor, Wirth says.
Most patients with HPV-related oral cancers are diagnosed in their 50s. That’s at least 10 years earlier than smoking-related oral cancers are diagnosed, Wirth says.
Given that cancers typically take decades to develop, it’s likely that their original infection occurred in early life.
Q. Is HPV sexually transmitted?
While the viruses can be found in saliva, HPV appears to be mostly spread through sex, rather than more casual contact such as kissing, according to the study in the Journal of the American Medical Association.
HPV is the most common sexually transmitted infection in the world, according to the National Cancer Institute, another co-sponsor of the January report. Most sexually active people become infected at some point.
Oral HPV infections were more than eight times more common among people who have had sex — defined as vaginal, oral or anal intercourse — than among people who have never had sex, according to the JAMA study. The infections were also more common in people who had more sex partners and who began having oral sex as teenagers. Fewer than 1% of people without sexual experience had an oral HPV infection, suggesting that the virus is not easily transmitted through deep kissing.
Q. Can HPV infections be prevented?
A. Yes. The new HPV vaccines — recommended for both boys and girls at age 11 or 12 — have been shown to protect against cervical, vaginal and vulvar cancers. One of the vaccines also protects against strains of HPV that cause genital warts.
Q. Does the HPV vaccine prevent oral cancer?
A. Researchers haven’t tested HPV vaccines on oral cancers, and aren’t likely to, Wirth says. Researchers would have to follow study participants for 30 or 40 years to detect any difference in oral cancer rates. Scientists were able to detect a reduction in cervical precancers, however, after only six or seven years.
Still, animal tests suggest that an HPV vaccine would likely work in oral cancer. That’s because both approved vaccines block HPV 16, a subtype of the virus that causes most of of these cancers. Wirth says society may have to wait decades to see if oral cancer rates decline in communities with high HPV vaccination rates.
The vaccines cost about $390 for three shots.
In an accompanying editorial in JAMA last year, Drexel University’s Hans Schlecht wrote that doctors should counsel patients who have oral sex to use barrier protection, such as a condom or other device. Schlecht, an infectious-disease specialist, said doctors also should look out for early signs and symptoms of throat cancer.