Human papilloma virus (HPV) has gained a great deal of attention in the gynecologic literature over the past decade, primarily as it relates to abnormal pap smears. HPV is a sexually transmitted virus that is extremely common, especially in reproductive age women less than 30 years of age.
It is estimated that 80 percent of sexually active women will have HPV at some point in their lifetime. At any given moment in time, 25-30 percent the population between ages 14 and 59 can be found to harbor the virus. However, the highest prevalence occurs in women between the ages of 20-24, where it approaches 45 percent.
The primary mode of transmission is through sexual contact, including oral sex. Unfortunately, prevention of transmission is extremely difficult. Unlike other commonly known sexually transmitted infections (such as chlamydia, gonorrhea, herpes, HIV), condoms and other barrier methods are not very effective at preventing the spread of HPV. Consequently, other than abstinence, our ability to curtail the transmission of HPV is extremely limited. Education is therefore our best weapon against the virus and its potential impact on our health.
To begin with, there are more than 50 different subtypes of HPV. Some of these are referred to as “oncogenic,” meaning they have the ability to transform normal cells into cells that have the potential to become cancerous. We refer to these abnormal cells as “dysplasia.” Fortunately, most of the time dysplasia either resolves on its own or it can be removed before getting the chance to progress to cancer.
The pap smear has traditionally been the test we use to help screen patients for dysplasia. Over the past decade, additional tests that can detect oncogenic HPV have become commonplace and are now often performed in conjunction with pap smears.
In March 2013, the American Society for Colposcopy and Cervical Pathology (ASCCP) issued new guidelines on the use of HPV testing and management of abnormal pap smears. These guidelines were also endorsed by the American College of Obstetricians and Gynecologists. It is also important to recognize that they are based on a significant amount of scientific research devoted to understanding the attributes and natural history of HPV.
So what has the research shown? First, we have learned that the majority of women who acquire HPV actually clear the virus on their own within 1-2 years. This is great news! Second, it is the person who has persistence of the virus that seems to be at risk for developing dysplasia, or the abnormal cells mentioned above. Third, the majority of women who develop dysplasia will not go on to develop cervical cancer, though the likelihood increases with the severity of dysplasia (not a surprise).
We typically divide dysplasia into low grade and high grade. Those with low grade have a 1 percent chance of developing cervical cancer if left untreated. Those with high grade have a 10 percent chance. Therefore, it is important to identify women who either have high grade dysplasia or who are at risk for developing it.
We have also learned that two HPV subtypes, #16 and #18, are associated with approximately 70 percent of all cervical cancers. This knowledge can help us further identify patients who may benefit from heightened surveillance. Finally, we have learned that from the time someone first acquires HPV, it typically takes 20 years or more before a cancer will develop, if at all.
So what are some of the new recommendations resulting from the latest research? First, because of the very long time it takes to develop a cervical cancer, we no longer need to be doing routine pap smears every year. Starting at age 21, we now perform pap smears every 3 years until the age of 30. For those in this age group who are found to have certain abnormalities, we may choose to run an HPV test (which can be done on the same specimen). This will help us identify those who may need further evaluation to determine if they have dysplasia.
For women over age thirty, we now recommend obtaining an HPV test in addition to the pap smear. If both are negative, then the likelihood of having dysplasia is almost zero. Again, because of the 20 plus years it takes to develop a cervical cancer after acquiring HPV, the next pap smear would not need to be for another five years. For those who have a normal pap but with a positive HPV test, we can either repeat the pap in one year, or determine if they have either subtype 16 or 18, in which case we can do additional testing. Finally, if someone has reached the age of 65, we can stop doing pap smears if they have been normal with negative HPV testing for the previous 10 years.
These guidelines are admittedly a little complicated to follow. But implementing them will lead to better patient care and prevent many unnecessary procedures. No doubt, recommendations are sure to evolve as we continue to learn more about HPV and how it relates to cervical cancer screening and the management of dysplasia. Your gynecologist is an excellent resource for additional information. You can also learn more online at the websites of the American Society for Colposcopy and Cervical Pathology and the American College of Obstetricians and Gynecologists.
Author James Bunker, MD is board certified in obstetrics and gynecology. He practices at Four Seasons OBGYN and Midwifery, a department of Brattleboro Memorial Hospital. He can be reached at 802-251-9965.