Condoms protect women against HPV infection
Results from a new study indicate that consistent condom use offers protection against high-risk and low-risk types of human papillomavirus (HPV).1 While a quadrivalent HPV vaccine has just come on the U.S. market, providers still will need to emphasize that consistent condom use will help protect against other high-risk types of HPV that put women at risk for cervical cancer, says Rachel Winer, PhD, lead author of the research paper and research associate in the Department of Epidemiology's HPV Research Group at the University of Washington in Seattle.
The approved quadrivalent HPV vaccine (Gardasil; Merck & Co., Whitehouse Station, NJ) protects against four HPV genotypes: 6 and 11, which cause about 90% of genital warts, and 16 and 18, which account for about 70% of cervical cancers worldwide, explains Winer. "There are at least 15 known cancer-causing HPV genotypes, so while the vaccine is expected to have a major impact on reducing rates of cervical cancer, women will still be at risk for acquiring other cancer-causing types," she notes.
Even with the HPV vaccine now in hand, not all women will get vaccinated, says Winer. The approved indication for Gardasil is for girls and women 9 through 26 years of age. While females who are sexually active also may benefit from the vaccine, they may get less benefit since they already may have acquired one or more vaccine HPV types. Condom use can help protect against HPV infection, states Winer. Even with vaccines and condom use, regular screening still will be important as well, she adds.
To conduct the study, investigators evaluated 82 female university students who reported their first intercourse with a male partner during the study period or within two weeks before enrollment. Cervical and vulvovaginal samples were collected every four months for HPV DNA testing and Papanicolaou testing. Women used electronic diaries to enter information about their daily sexual behavior.
When data were analyzed, genital HPV infection was calculated at 37.8 per 100 patient-years at risk for women whose partners used condoms for all instances of intercourse during the eight months before testing, compared with 89.3 per 100 patient-years at risk for women whose partners used condoms less than 5% of the time (adjusted hazard ratio, 0.3; 95% confidence interval, 0.1-0.6, adjusted for the number of new partners and the number of previous partners of the male partner).
When investigators restricted the analysis to high- and low-risk types of HPV and HPV types 6, 11, 16, and 18, similar associations were observed. For women reporting 100% condom use by their partners, there were no cervical squamous intraepithelial lesions detected in 32 patient-years at risk compared with 14 incident lesions detected during 97 patient-years at risk in women whose partners used condoms inconsistently or not at all.1
Study limitations include:
- difficulty in determining the optimal time frame for an assessment of risk factors for acquiring HPV infection;
- possible incomplete reporting creating a misclassification of the frequency of condom use;
- incomplete follow-up and delayed or missed clinical visits;
- lack of generalizability to populations of older women or women of lower socioeconomic status.1
What are the take-home messages from this study? Ward Cates, MD, MPH, president of the Institute for Family Health at Family Health International (FHI), Research Triangle Park, NC, and co-author of a companion editorial to the research paper, offers three possible points:
- Condoms, when used consistently and correctly, are effective in reducing the risks of becoming infected with sexually transmitted infections (STIs), including HPV.
- Condoms need to be an essential part of the full spectrum of prevention approaches.
- Other complementary prevention approaches need to be emphasized, even when condoms are part of the mix, such as avoiding any sexual risk, safer behavioral practices, better partner choices, and STI treatment.
"Condom use is only one of a growing array of methods for reducing the risks associated with sexual activity and should be targeted to groups in which sexual exposure to infection is likely," wrote Cates and co-author Marcus Steiner, PhD, senior epidemiologist at FHI. "When used consistently and correctly, condoms also reduce the risk of unintended pregnancy. Condoms are just one tool in the armamentarium against sexually transmitted infections; only by harnessing all the evidence-based prevention tools can we move toward true sexual health."2
References
1. Winer RL, Hughes JP, Feng Q, et al. Condom use and the risk of genital human papillomavirus infection in young women. N Engl J Med 2006; 354:2,645-2,654.
2. Steiner MJ, Cates W. Condoms and sexually transmitted infections. N Engl J Med 2006; 354:2,642-2,643.
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