She said the study also failed to consider the reduction in the burden of male diseases if boys were vaccinated. "This is an important public health estimate, and one that is meaningful for making public policy and clinical recommendations," she said.
Dr. Erich M. Sturgis, an associate professor of head and neck surgery at the University of Texas M. D. Anderson Cancer Center in Houston, thinks Kim's group has underestimated the number of head and neck cancers attributable to HPV infection.
"We see these patients suffering every day with the treatment, and patients dying of this disease," Sturgis said. "I think the proportion of oropharyngeal cancers that are attributable to HPV is a clear underestimate in the study."
The Harvard team attributes about 30 percent of these cancers to HPV, but the latest data shows it's really 60 percent to 70 percent, he said. "If it's cost effective to vaccinate girls against cervical cancer in the United States, I think it would be cost-effective to vaccinate boys to prevent oropharyngeal, pineal and anal cancer," he said.
Merck & Co., maker of Gardasil, has petitioned the FDA to approve the vaccine for boys to prevent genital warts. Jennifer Allen, a Merck spokeswoman, said the company's data is at odds with the study numbers.
"The Merck health economic analysis shows that vaccinating males with Gardasil is cost effective at a per quality-adjusted life year of less than $25,000," Allen said. "Our model is based on data from our clinical trials, as well as data we gathered after the approval of Gardasil," she said.
Gardasil, approved for girls in 2006, covers four types of HPV, two of which cause about 70 percent of cervical cancers worldwide.
Since Gardasil's approval, studies have found it safe and nearly 100 percent effective in preventing precancerous cervical lesions from the four HPV strains targeted by the vaccine.
Studies have also found that Gardasil far more effective when given to girls or young women before they become sexually active.
For more information on HPV vaccine, visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Jane Kim, Ph.D., assistant professor, health decision science, Harvard School of Public Health, Boston; Philip E. Castle, Ph.D., M.P.H., investigator, division of cancer epidemiology and genetics, U.S. National Cancer Institute, Bethesda, Md.; Anna R. Giuliano, Ph.D., chair, department of cancer epidemiology and genetics, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Fla.; Erich M. Sturgis, M.D., associate professor, head and neck surgery, University of Texas M. D. Anderson Cancer Center, Houston; Jennifer Allen, spokeswomam, Merck & Co., Whitehorse Station, N.J.; Debbie Saslow, Ph.D., director, breast and gynecologic cancer, American Cancer Society; Oct. 9, 2009, British Medical Journal online