Rewire is dedicated to publishing evidence-based information on sexual and reproductive health, rights, and justice issues.  This article examines the basics on Human Papillomavirus and its relationship to cervical cancer based on findings applicable to women in the United States.

What is HPV?

The Human Papillomavirus (HPV) is the most commonly diagnosed sexually-transmitted infection (STI) in the United States. At any given time, 26.8 percent of women between ages 14 and 59 have an active HPV infection, and approximately 75 percent of all sexually active individuals will contract HPV at some time in their lives. 

There are at least 120 different strains of HPV virus. Some of these cause cervical, anal, genital and oral pre-cancerous lesions and cancers.  Others cause genital warts.  The strains are divided into low-risk and high-risk types, with the high-risk types associated with cervical lesions and cancers and the low-risk types generally associated with genital warts.  Because there are many different kinds of HPV, it is possible to be infected with more than one type at a time.

How do you get HPV?

HPV is transmitted through genital contact, especially during vaginal or anal intercourse.  It can also be transmitted by oral sex.  Condoms decrease the risk of getting HPV, but not completely.

How does HPV cause cancer?

Cancer is caused by abnormal cell growth, and viruses like HPV increase the likelihood of this abnormal growth.  High-risk strains of HPV are responsible for all cervical cancers, most anal cancers, and some vaginal, penile, and throat cancers.  Researchers are not entirely sure why HPV causes pre-cancer or cancer in some men and women and disappears spontaneously in the majority.  Despite this, our bodies usually have an immune response that attacks the virus and removes abnormal cells.  Some people with HPV have an immune response that clears it, some progress to slightly abnormal cells then clear it, and some even progress to pre-cancerous lesions which then resolve spontaneously.  The longer your body is exposed to the virus, the more likely abnormal cells will grow.  This is why we say that it is persistent HPV infection that is associated with cancer, rather than the transient infection most people have.  Developing cervical cancer takes years.  The younger you are, the more likely you are to clear the infection and the virus.  Some people with immune problems, like HIV, are less likely to be able to get rid of the abnormal cells on their own and require more frequent pap smears.

How do I know if I have HPV?

Most doctors will do automatic HPV testing on certain women getting pap smears.  While we used to perform HPV testing on all women getting a pap, most doctors now test women under 30 only if they have abnormal pap smears and all women over 30.  The reason we don’t test women under 30 who have normal paps is that many women have transient HPV infections; if the infection hasn’t caused any abnormal cells, it isn’t important to know if it’s there or not.  Women over 30, on the other hand, are likely to continue to have an HPV infection, because they’re the women whose body didn’t get rid of the infection when they were in their 20s. (remember that most women contract HPV when they’re in their teens and twenties, when they first start having sex).  Women over 30 with positive HPV results undergo yearly pap smears, and sometimes other testing, until the HPV becomes negative.  We only test for certain strains of HPV (those most likely to cause cervical cancer).  Since cervical cancer is only caused by high-risk strains of HPV, and because even with the presence of HPV it takes years to develop cancer, women over 30 who have a normal pap and have a negative HPV test can safely change to screening every 3 years.

I have HPV.  What do I do now?

The good news is that most women’s immune systems will eliminate the virus. Among young women, about 90 percent will clear the virus within a year.  That means that the vast majority of women who get HPV will never have any negative effects; that is, they will never develop pre-cancerous lesions, cancer, or genital warts.  If you found out you have HPV during a pap test, consult with your provider to determine what the next course of action is.  You and your partner can discuss using condoms or other barrier methods to prevent transmission of the virus; however, your partner may well already have had the same strain of the virus that you have, or might have another strain.  Remember that the virus is very prevalent and in most cases causes no harm.

What about the HPV vaccine?

There are currently 2 vaccines available against HPV: one covers types 6 and 11 (common causes of genital warts) and types 16 and 18 (the most common causes of cervical cancer), the other covers HPV types 16 and 18 only.  They are currently recommended for women starting at age 11-12 and men age 9 to 18.   (Keep in mind that these are recommendations from the US Centers for Disease Control; vaccination has been shown to be safe starting at age 9 for young women as well, and has been FDA-approved up to age 26).  A course of three shots is necessary for the best response.  Ideally the series of 3 shots should be completed before starting to have any sexual activity, including oral sex or non-penetrative sex, since all kinds of sexual contact can lead to HPV infection. 

Remember that there are dozens of strains of the HPV virus; these vaccines cover the most common strains that are likely to cause abnormal cervical cells that can turn into cancer if not treated.  They also appear to help protect against some of the other strains.  These vaccines have been shown to decrease the rate of abnormal pap smears and genital warts in women, and to decrease the rate of genital warts and some anal cancers in men.

What about men?

The vaccines are effective in men as well, to prevent genital warts and anal cancers, and appear to be cost-effective when given to men before they start having sexual contact.  Not all insurers are paying for the vaccine for young men yet, which could leave you with a substantial out-of-pocket cost.  Right now it’s considered an optional vaccine for young men rather than recommended; this will likely change as more studies are done regarding the long-term effectiveness of the vaccine.  Note that the vaccine that covers just HPV-16 and HPV-18 is not recommended for men at this time (because types 16 and 18 cause cervical cancer in women but don’t appear to cause any problems for men).  The vaccine that also covers HPV-6 and HPV-11 (which cause genital warts) is appropriate for men to prevent genital warts.

What if I’m over 26 and want the vaccine?

There is no reason why you can’t get one of the HPV vaccines even if you’re over 26; however, you will probably have to pay for it yourself, as it’s not a recommended service.  If you haven’t started to have sex yet it may be a worthwhile investment for you.  If you’ve already had several partners, it may not be worthwhile, as you’ve probably already been exposed to several different types of HPV.

Why do I still need pap smears even though I’ve been vaccinated?

There are many forms of HPV that can cause cervical cancer and the vaccine is only effective against the two most common forms.  Because of this you will continue to need pap smears because at this time we don’t have enough long-term information to know if that can change.  For now, young women who have been vaccinated still should get pap smears at the same intervals recommended for those who have not been vaccinated.  It appears that women who have been vaccinated are less likely to have abnormal pap smears and therefore less likely to need further testing such as colposcopy.  In the future we may know more about the effects of the vaccine and be able to change these recommendations.