Tobacco users are more likely than others to test positive for oral human papillomavirus type 16 (HPV-16),according to a report online Tuesday in JAMA.
“We know from other research that most people who have HPV clear that infection after about a year,” said Gypsyamber D’Souza, the report’s senior author from Johns Hopkins Bloomberg School of Public Health.
Some people may be more likely to get the infection or have trouble fighting it off, however. Tobacco users may be among that group, D’Souza said by phone.
D’Souza and her coauthors used data on 6,887 adults age 18 to 59 who had been tested for HPV infection, reported their recent nicotine use and had given blood and urine samples to be tested for nicotine and tobacco markers as part of a national survey conducted from 2009 to 2012.
Almost 30 percent were current tobacco users, who were more likely than nonusers to be male, younger, less educated and to have a higher number of lifetime oral sexual partners.
Two percent of current tobacco users had the infection, compared to less than one percent of never or former tobacco users.
Based on the blood tests, with every additional three cigarettes smoked per day, the risk for HPV-16 infection increased by 31 percent.
“We saw a very strong association between higher levels of tobacco use and increased oral HPV prevalence across each of the biomarkers we evaluated and even at low levels of tobacco use, which would represent casual use or secondhand smoke,” D’Souza said.
Using biomarkers took away the uncertainty inherent in self-reported tobacco use, she noted.
Oral HPV-16 infection is not common in the population and testing positive for the infection does not mean those people went on to develop cancer, but a 30% increase in risk represents an important difference, D’Souza said.
Tobacco may suppress the immune system and make it harder for the body to fight off the infection, she and her colleagues write.
“It’s not known why (HPV-16) persists in some people,” D’Souza said. “This suggests that tobacco may have a role in why they might be unlucky enough not to have cleared the infection.”
Dr. Carole Fakhry, who worked with D’Souza on the study at the Johns Hopkins University School of Medicine, said the infection is rare.
“The associated cancer is also rare, but increasing in the United States and abroad,” she said.
Smokers tend to have more sexual partners and risky sexual practices than nonsmokers, said Xavier Bosch, a public health and cancer epidemiology expert at the Catalan Institute of Oncology in Barcelona. He was not part of the new study.
There was still a link between tobacco and HPV infection even when sexual behavior was accounted for, D’Souza said. That suggests that riskier sexual behavior doesn’t fully explain the connection.