Aug. 1, 2009— -- In what some doctors are calling the most important development in head and neck cancer in decades, researchers have discovered that head and neck cancers caused by the human papillomavirus, otherwise known as HPV, are more survivable than other forms of head and neck cancer.
Having an HPV-positive tumor was associated with significantly longer overall survival in two different studies, according to Dr. Kevin Cullen, director of the Greenebaum Cancer Center of the University of Maryland in Baltimore, and colleagues.
The finding also helps to explain why black Americans with throat cancer, otherwise known as oropharyngeal cancer do worse than whites, the researchers said in the September issue of the journal Cancer Prevention Research.
At a press conference Wednesday, Cullen and other experts told reporters that the finding should change practice. "We are now testing for HPV, which we weren't doing even a few months ago," Cullen said.
HPV testing for patients with throat cancer has implications for both prognosis and treatment, he said.
Overall, Cullen said, blacks are known to have worse outcomes for a type of cancer known as squamous cell carcinoma of the head and neck, although the reasons for the differences have not been entirely clear.
"This is the first clue that it may be biologic rather than related to issues of access, insurance or provider attitudes," he said.
The "paradox," Cullen told reporters, is that "HPV may cause some of these cancers, but HPV-positive cancers behave biologically very well -- they are very responsive to chemotherapy and radiation."
He said the virus is not protective, but instead gives rise to cancers that are more vulnerable to treatment with chemotherapy and radiation than are those caused by tobacco and alcohol use.
Research Explains Race Difference in Throat Cancer Survival
The black-white difference is caused by significantly lower rates of oral HPV among blacks, which may be a function of differing sexual practices, Cullen said during the press conference.
Indeed, acquiring an HPV infection through genital sex would tend to protect a person against a subsequent oral infection and vice versa, according to Dr. Otis Brawley, chief medical officer of the American Cancer Society.
Brawley told reporters that there is some evidence of racial differences in sexual behavior risks, especially among teenagers.
The U.S. Centers for Disease Control and Prevention, he said, has found "distinct preferences" among young whites for oral sex as their initial sexual activity and among black youths for genital sex.
Such a difference in behavior "makes a lot of sense in terms of causation," he said.
In the current study, the researchers first analyzed a retrospective cohort of 106 white and 95 black patients with squamous cell carcinoma of the head and neck and found that median overall survival was 52.1 months for whites and 23.7 months for blacks.
The difference was due entirely to overall survival in the subgroup with oropharyngeal cancer, where whites had a median overall survival of 69.4 months and blacks just 23.7 months.
The study makes an "extremely important finding that has tremendously important public health implications," according to Dr. Scott Lippman of M.D. Anderson Cancer Center in Houston, editor of the journal.
"It's the most important development in head and neck cancer that I've seen in the past 30 years," he said.
For doctors, Brawley said, the study "will change how we practice. Everybody will now want to look at their head and neck cancers and analyze them for HPV."
He noted that the study implies that the apparent black-white difference in outcomes is really a difference in who is infected with HPV.
"It's a landmark paper for two reasons," said Dr. Martin Blaser of New York University Langhorne Medical Center, an expert in the links between infectious agents and cancer.
More Clues for Virus-Linked Cancers
First, he said, it clarifies the links between the disease and racial differences in outcomes. But the research also has implications for understanding the biology of cancer and the links with infectious agents, he added.
"This study is important because it helps explain both cancer causation," he said, "and also differences in incidence and outcome."