WASHINGTON (AP) — A prolonged sore throat once was considered a cancer worry mainly for smokers and drinkers. Today there‘s another risk: A sexually transmitted virus is fueling a rise in oral cancer.
The HPV virus is best known for causing cervical cancer. But it can cause cancer in the upper throat, too, and a new study says HPV-positive tumors now account for a majority of these cases of what is called oropharyngeal cancer.
If that trend continues, that type of oral cancer will become the nation’s main HPV-related cancer within the decade, surpassing cervical cancer, researchers from Ohio State University and the National Cancer Institute report Monday.
“There is an urgency to try to figure out how to prevent this,” says Dr. Amy Chen of the American Cancer Society and Emory University, who wasn‘t part of the new research.
While women sometimes get oral cancer caused by the HPV, the risk is greatest and rising among men, researchers reported in the Journal of Clinical Oncology. No one knows why, but it begs the question of whether the vaccine given to girls and young women to protect against cervical cancer also might protect against oral HPV.
HPV vaccination is approved for boys to prevent genital warts and anal cancer, additional problems caused by human papillomavirus. But protection against oral HPV hasn’t been studied in either gender, says Dr. Maura Gillison, a head-and-neck cancer specialist at Ohio State and senior author of the new research. That‘s important, because it’s possible to have HPV in one part of the body but not the other, she says.
A spokeswoman for Merck & Co., maker of the HPV vaccine Gardasil, said the company has no plans for an oral cancer study.
Monday‘s research was funded by the NCI and Ohio State. Gillison has been a consultant to Merck.
There are nearly 10,000 new cases of oropharyngeal cancer a year, and overall incidence has risen by 28 percent since 1988 even as other types of head-and-neck cancer have been declining.
Tobacco and alcohol have long been the main causes of these tumors, which occur in the tonsils, base of the tongue and upper throat. But over the past few years, studies have shown HPV is playing a role in that rise, probably due to an increase in oral sex even as tobacco use was dropping.
The new study took a closer look, tracking HPV over time by directly testing tumor tissue from 271 patients that had been stored in cancer registries in Hawaii, Iowa and Los Angeles. The proportion that were HPV-positive rose from just 16 percent in the late 1980s to nearly 73 percent by the early 2000s.
Translate that to the overall population, and the researchers concluded that incidence rates of the HPV-positive tumors more than tripled while HPV-negative tumors dropped by half.
Oral cancer has always been a bigger threat to men than women. Gillison says women account for only about 1 in 4 cases, and their incidence is holding steady while men’s is rising. That raises questions about gender differences in sexual behavior or whether oral HPV infection is likely to linger longer in men.
While HPV is the most common sexually transmitted infection, studies show women‘s bodies usually clear the virus from the cervix quickly; only an infection that persists for years is a cancer risk. It’s not known if oral HPV acts similarly or even is as common.
Nor is it clear if oral sex is the only way it‘s transmitted, cautions Dr. Gregory Masters of the American Society for Clinical Oncology, an oncologist at Delaware’s Helen Graham Cancer Center.
Regardless, just over 11,000 cases of cervical cancer will be diagnosed this year, a number that has been dropping steadily thanks to better Pap smears. (It‘s too soon to know what difference vaccination will make.) Gillison’s team calculated that annual cases of cervical cancer will drop to 7,700 by 2020 — compared with about 8,700 cases of HPV-positive oropharyngeal cancer by then, about 7,400 of them in men.
The cancer society‘s Chen urged caution about those numbers, saying more data is needed. But she says two things are clear: First, patients with HPV-linked oral tumors have better survival odds than those with other types of this cancer, possibly because they tend to be younger. Studies are beginning to test if they can scale back today’s treatment and thus suffer fewer long-term side effects such as problems with speech and swallowing.
And “just because you‘re not a smoker or drinker doesn’t mean you can‘t get throat cancer,” Chen says — so get checked for symptoms like a throat that’s sore for longer than two weeks.
<한글기사>
오럴섹스로 구강암 발병 증가
오럴섹스를 통한 바이러스 감염으로 인해 구강암에 걸리는 사례가 현격히 늘었다는 연구 결과가 나왔다고 뉴욕타임스(NYT) 등이 3일(현지시각) 보도했다.
임상종양학저널(Journal of Clinical Oncology)에 실린 논문에 따르면 오하이오 주립대 모라 길리슨 등 연구자들은 1984~2004년 구강암 진단을 받은 종양 샘플 271개를 조사했다. 1980년대 샘플의 16%에서 인유두종바이러스(HPV)가 발견됐으나 200년대의 샘플에서는 HPV가 검출된 비율이 72%에 달했다.
생식기에 감염되는 HPV는 여성들에게서 발견되는 자궁경부암의 주원인으로 알려 졌다.
뉴욕타임스에 따르면 연구자들은 HPV로 인한 구강암이 1988년 10만명당 0.8명에 서 2004년에는 10만명당 2.6명으로 증가한 것으로 추산했다.
이 같은 추세가 계속된다면 2020년에는 바이러스성 구강암에 걸린 남성의 숫자가 여성 자궁경부암 환자보다 더 많아질 것이라고 말했다.
미국과 다른 나라의 의사들은 이미 HPV로 인한 구강암 발병이 늘고 있다는 것을 파악했으나 실제로 어느 정도인지는 이번 연구를 통해 확인됐다고 NYT는 전했다.
블룸버그 통신에 따르면 최근까지 구강암은 주로 나이 든 사람들이 담배와 알코 올 때문에 걸리는 것이었으나 HPV 때문에 편도선, 입천장, 혀 등에 주로 생기는 암은 30~50대의 남성에게 많이 생긴다고 글리슨은 설명했다. 그는 이 병에 걸리는 여성이 남성보다 훨씬 적은 이유는 아직 모른다고 덧붙였다.
길리슨은 “HPV가 유발하는 암의 부담은 앞으로 10년간 여자로부터 남자에게로 이동할 것”이라면서 “섹스 파트너 수가 늘어나는 동안 HPV 감염이 증가했다”고 말했다.
논문에 따르면 HPV에 음성인 구강암이 줄어드는 것은 미국에서 흡연율이 하락하 는 현상을 반영한다.
길리슨과 동료들은 2007년 ‘뉴잉글랜드 저널 오브 메디신’에 발표된 연구에서도 구강 또는 성기를 이용한 성행위 상대가 많이 있으면 HPV 관련 구강암에 걸릴 수 있다고 경고한 바 있다. 글리슨은 인터뷰에서 딥 키스를 통해서도 암에 걸릴 수 있다 고 말했다.
