The female hormone estrogen may have a role in HPV viral infection, strains of which are implicated in cervical cancer, shows research in Sexually Transmitted Infections.
Human papillomavirus (HPV) infection is a common genital infection seen most often in young women and adolescents. There are often no visible signs of infection.
Researchers from the University of Minnesota (M. L. Shew, R. McGlennen, N. Zaidi, M. Westerheim, M. Ireland and S. Anderson) tested 175 sexually active women for HPV infection during routine examinations at a sexual health clinic. The women were all aged between 14 and 44. Over half were younger than 25.
They also investigated how many estrogen receptors -- cells that are specifically activated by the female hormone -- were present in the neck of the womb (cervix). The women also completed a questionnaire, detailing their sexual and menstrual histories.
Four out of 10 women tested positive for HPV, mostly HPV 16, the strain linked to cervical cancer. Six women had two strains, and one had three. The younger the woman, the greater was her risk of infection. But starting sex at an early age was not a high risk factor for the infection, the research showed.
Almost all the women with HPV infection had detectable levels of estrogen receptors. Every 10 per cent increase in receptor numbers tripled the likelihood of HPV infection.
Clearly, say the authors, younger women will have higher estrogen levels than older women, but there was no obvious association between menstrual cycle -- at certain times of which circulating estrogen levels are higher -- and the numbers of estrogen receptors detected. And the association between estrogen receptors and HPV held for older women as well.
It may be that some women are "biologically vulnerable" to HPV because of the numbers of estrogen receptors they have in their cervix, say the authors, suggesting that these receptors may in some way facilitate infection with the virus.
The full article is available in PDF format at this URL.
(Reference: Oestrogen receptor transcripts associated with cervical human papillomavirus infection 2002; Sexually Transmitted Infections 78:210-14.)
[Contact: Marcia L Shew MD MPH]