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05/31/2011 in news
A sharp rise in a type of throat cancer among men is increasingly being linked to HPV, the sexually transmitted human papillomavirus that can cause cervical cancer in women.
A new study from the National Cancer Institute warns that if recent trends continue, the number of HPV-positive oral cancers among men could rise by nearly 30% by 2020. At that rate, it could surpass that of cervical cancers among women, which are expected to decline as a result of better screening.
The study is to be presented this week at the annual American Society of Clinical Oncology meeting.
Between 1988 and 2004, the researchers found, the incidence of HPV-positive oropharynx cancers—those that affect the back of the tongue and tonsil area-increased by 225%. Anil Chaturvedi, a National Cancer Institute investigator who led the research, estimates there were approximately 6,700 cases of HPV-positive oropharynx cancers in 2010, up from 4,000 to 4,500 in 2004, and cases are projected to increase 27% to 8,500 in 2020.
Recent studies show about 25% of mouth and 35% of throat cancers are caused by HPV, according to the Centers for Disease Control and Prevention.
Men account for the majority of cases, and currently the highest prevalence is in men 40 to 55, says Eric Genden, chief of head and neck oncology at Mount Sinai Medical Center in New York. Studies have shown that the cancer can show up 10 years after exposure to HPV, which has become the most common sexually transmitted virus in the U.S.
"We are sitting at the cusp of a pandemic", says Dr. Genden.
Dr. Chaturvedi says more studies are needed to evaluate whether a vaccine now used to prevent HPV for genital warts and genital and anal cancers can prevent oral HPV infections.
The HPV vaccine, Gardasil, made by Merck & Co., was approved in 2006 for girls and young women up to age 26, but while it is routinely recommended, only about 27% of girls have received all three doses needed to confer protection.
The FDA in 2009 approved the vaccine for males ages 9 through 26 to reduce the risk of genital warts, and in 2010 approved it for both sexes for the prevention of anal cancers. However, the CDC has only a "permissive", recommendation for boys, rather than a routine recommendation, meaning doctors generally will only administer it if parents or patients ask for it, says Michael Brady, chairman of the American Academy of Pediatrics infectious disease committee.
Lauri Markowitz, a CDC medical epidemiologist, says the CDC advisory committee that sets vaccine recommendations will review new data related to the issue at a meeting next month. However, at present there aren't any clinical-trial data showing the effectiveness of the vaccine against oral infections, she says.
A Merck spokeswoman says the company has no plans to study the potential of Gardasil to prevent these cancers.
Researchers say it isn't clear why men are at higher risk for HPV-positive oral cancers. But for both men and women a high lifetime number of sex partners is associated with the cancer.
Changes in sexual behaviors that include increased practice of oral sex are associated with the increase, but a 2007 New England Journal of Medicine article also said engagement in casual sex, early age at first intercourse, and infrequent use of condoms each were associated with HPV-positive oropharyngeal cancer. Mouth-to-mouth contact through kissing can't be ruled out as a transmission route.
Most infections don't cause symptoms and go away on their own. But HPV can cause genital warts and warts in the throat, and has been associated with vaginal, vulvar and anal cancers.
Anna Giuliano, chairwoman of the department of cancer epidemiology at the Moffitt Cancer Center in Tampa, Fla., who studies oral HPV infections of men in several countries, says the rise in cancers among men shows it is important for males, as well as girls, to be vaccinated.
Doctors typically don't test for HPV-positive oral cancers. But Jonathan Aviv, director of the voice and swallowing center at New York's ENT and Allergy Associates, says his group looks through a miniature camera inserted through the nose at the back of the throat and tongue, and can biopsy suspicious warts or tumors.
In addition to being asked about symptoms such as hoarseness, difficulty swallowing, a neck mass or mouth sore that won't heal, patients are asked to fill out a risk-assessment sheet that includes the number of lifetime oral-sex partners. "People do get upset sometimes, but if your sexual history puts you at an increased risk for HPV, you should go and see an ear, nose and throat doctor", says Dr. Aviv.
Fortunately, says Mount Sinai's Dr. Genden, those with HPV-positive oral cancers have a disease survival rate of 85% to 90% over five years, higher than those with oral cancers that aren't linked to HPV, but are more commonly linked to alcohol use, tobacco, and radiation exposure.
Philip Keane, a 52-year-old photographer and partner in a marketing firm, found a lump on his neck while shaving, which was initially misdiagnosed as an infection. A scope of his throat showed it was HPV-positive throat cancer. Dr. Genden removed it last July using minimally invasive robotic surgery, and Mr. Keane had 6½, weeks of daily radiation after that, which left him cancer-free.
At first surprised and embarrassed, Mr. Keane says he has no reason to think he was at high risk, while he has young daughters who have been immunized "I didn't know about HPV in men.", He plans to have his 12-year-old son immunized as well.
Human papillomavirus is the most common sexually transmitted virus in the U.S.
By LAURA LANDRO
Source: Centers for Disease Control and Prevention, American Academy of Pediatrics