Study also suggests that low incidence of HPV-positive throat cancers in blacks may explain poor survival rates
Cancer of the throat that stems from a human papillomavirus infection responds to treatment better than throat cancer that’s triggered by other causes, researchers report online July 29 in Cancer Prevention Research.
The scientists also find that blacks are less likely than whites to have throat cancer that’s attributable to HPV, which may explain why the cancer also proved more deadly in blacks in this study.
Throat cancer, formally known as oropharyngeal cancer, includes malignancies at the base of the tongue, on the tonsils, in the back of the mouth or on the walls of the throat. The cancer has been linked to smoking and alcohol use, but it can also arise from HPV infections acquired via oral sex (SN: 5/12/07, p. 291).
In the new study, researchers analyzed two sets of people with throat cancer.
One group included 196 whites and 28 blacks participating in an ongoing international medical trial. While 66 of the white patients had HPV-positive cancer, only one of the blacks did. All received chemotherapy and radiation.
Looking at survival among these patients over more than five years, the researchers found that HPV-negative throat cancer patients had a median survival of only 20 months. Race didn’t change this data significantly.
In contrast, patients with HPV-positive throat cancer lived substantially longer. Their median survival time could not be accurately discerned because many patients were still alive when the study data were analyzed, says study coauthor Kevin Cullen, a medical oncologist at the University of Maryland Medical Center in Baltimore. This bolsters previous studies showing HPV-positive throat cancer responds well to chemotherapy and radiation.
Cullen and his colleagues decided to examine survival rates among an additional group of patients treated for throat cancer in Baltimore. They identified 124 patients who had been monitored for more than five years, including 54 blacks and 70 whites. The two racial groups had comparable disease progression and received similar treatments. But median survival time for the whites was 69 months, compared with only 25 months for the blacks.
“The better outcome of white versus black oropharyngeal cancer patients in an equal-care setting can be explained by the larger proportion of white patients with better-prognosis HPV-positive tumors,” says oncologist Otis Brawley of the American Cancer Society in Atlanta, in a perspective article accompanying the report.
Differences in sexual practices are a very plausible explanation, he says. Brawley cites a survey showing that white males and females age 15 to 19 are more likely to engage in oral sex than are their black counterparts. Blacks that age are more likely than whites to have experienced genital-to-genital sex.
As the impact of HPV status on throat cancer becomes clearer, treatment for the malignancy will change, says Maura Gillison, a medical oncologist at Ohio State University in Columbus. Patients who test positive for HPV might get by with lighter doses of chemotherapy or radiation, she says.
But those with HPV-negative throat cancers — the kind brought on by smoking and alcohol — face a stiffer challenge because they benefit less from chemo and radiation.
“We’ve got to look at HPV-negative patients to see whether they have a good surgical option,” Cullen says.
Meanwhile, vaccines that prevent cervical cancer from HPV infection may have newfound value, Gillison says. “There is considerable optimism in the medical community that these vaccines will be effective in other sites,” including the throat, she says.
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