|Risks for HPV and Dysplasia|
by Laura Dolson
Now we know that HPV is very common, very contagious, and related to cancers and precancer - most especially those of the uterine cervix. Some of the most recent research is focusing on what factors are involved in the progression of HPV to cervical dysplasia, as well as separating the risks for HPV from those of dysplasia.
Such is the study that was published in the Journal of the American Medical Association recently (6/20/01) by Anna-Barbara Moscicki and her colleagues. For this research, a group of young women was tested at frequent intervals to find out who would get HPV, and of those who did, who would progress to low grade cervical dysplasia (LSIL).
When reading about any study, it's important to find out who was being studied, and exactly what factors are being analyzed. In this case, there are two key points to remember about the research participants: 1) they are young (13-21, though most were 18-21) and 2) they were recruited from a family planning clinic, so they were, for the most part, sexually active. The researchers are careful to point out that there may be different factors at work with regards to HPV and older women which have not been fully studied (this actually seems quite likely). It is also always important to remember that any one study does not tell the whole story. Different research has different strengths and weaknesses, and it is only with repeated research that the whole picture begins to emerge. That said, here are the key findings of this recent study.
The Numbers - Out of the 719 young women who completed the study, 172 had dysplasia (LSIL or HSIL) at the beginning of the study. They were excluded from further analysis, but we can be quite sure that almost all of them were positive for HPV. Of the remaining 547, all but 105 tested positive for HPV when they entered the study, and an additional 54 developed HPV during the course of the study. Thus, when we add the 172 with dysplasia to the 496 that were positive for HPV at some point, we get 688 out of the total 719, or a whopping 93% of participants who almost certainly were infected with HPV at some point.
Risks for HPV - The women who started out with no signs of HPV were retested over the course of the study, and the ones who became infected were compared with the ones who remained negative. The following were found to be significant risk factors:
*Sexual Activity - It's no great surprise that sexual activity is the most significant risk factor, but the degree of risk is startling: the researchers write that "risk increased nearly 10-fold for each new partner per month reported"!
*Genital Herpes Infection - Women who already had genital herpes were more likely to get HPV, all other factors being equal. The researchers think this may be because the herpes causes disruptions in the cervix which make it easier for HPV to get a foothold.
*Vulvar warts - Women who had vulvar warts were more likely to get cervical infections as well. (Warts are generally caused by different types of HPV than the oncogenic ones which are associated with dysplasia and cancer.)
Surprisingly, young women taking oral contraceptives (the Pill) were somewhat less likely to become infected with HPV. This is all the more interesting because the use of oral contraceptives has been linked to dysplasia and cancer in other studies. The authors of the study were very cautious about interpreting this association, and further research must be done before much can be said about this.
Risks for Dysplasia - The women in the study who were found to have HPV were tested for signs of dysplasia over the course of the research. Out of the 496 of these women who did not have dysplasia to begin with, 109 developed it during that time. The following were found to be significant risk factors for dysplasia:
*HPV Infection, including Length of Infection - HPV is the main risk factor for dysplasia, but most of the time, the immune system is able to clear the virus from the body. When the infection persists, dysplasia is most likely to occur. In this study, the risk of dysplasia was higher in the first two years after initial infection, but more so in the second year than the first. After the third year, the rates of dysplasia taper off dramatically. Again, the authors remind us that this study is looking at young women, and the pattern may be quite different for older women. Older women are thought to have some different factors, one possibility being latent infection.
*Smoking - Other than HPV, the number one risk factor for cervical dysplasia was found to be daily cigarette smoking. This has been found in many other studies, and the link seems certain. The researchers point out that nicotine and other chemicals resulting from the breakdown of tobacco in the system have been found in the cervical mucous.
Conclusions - One of the major points of this study is the conclusion that there are separate risk factors for HPV and dysplasia. In the past, it has been unclear which risk factors caused what, but this study makes a great contribution to our growing understanding.
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