Dear Dr. Jeff: If I get the Human papillomavirus (HPV) vaccine, will I still have to get annual Pap tests?- S.A.
Dear S.A.: The development of Gardasil, the new HPV vaccine, constitutes a huge breakthrough in women's health care. The more women that get it, the fewer women there will be that will get cervical cancer.
As historic as it is, however, Gardasil will not eliminate the need for regular Pap tests. Here's why.
Infection with HPV causes all warts, including genital warts. Of the over 100 sub-types of HPV that have been identified, about 30 of them cause infections of genital mucosal sites. Two of these subtypes?six and 11?cause very noticeable but painless, cauliflower-like growths. They have virtually no carcinogenic potential.
Two other subtypes of HPV, however'16 and 18?are the most prominent of the 16 "high-risk" subtypes. Together, they cause some 70 percent of cervical cancers and over 95 percent of the most aggressive and invasive cervical cancers. HPV 16 and 18 are also strongly associated with anal and rectal cancers. Most often, they cause no visible lesions at all. Sometimes, they cause a few small, flat growths to appear, which look very much like normal "skin bumps."
Genital HPV infections are among the most common STIs worldwide, with the highest rate of infection found in women under the age of 25. In this country, it is estimated that over 50 percent of sexually active people contract HPV at one time or another?possibly as many as 75 percent of college students. At any given point in time, 20 million Americans have genital HPV infections that can be transmitted to others. Over 6.2 million people become newly infected every year.
Less than 1 percent of those infected with HPV ultimately develop cancer. But given numbers like 20 million or rates like 50 percent, the risks add up quickly.
Every year, nearly 10,000 women in the United States are diagnosed with cervical cancer, and nearly 4,000 women die from this largely preventable disease. Worldwide, about 500,000 new cases of cervical cancer are diagnosed each year, and 250,000 women die. Cancer of the cervix is the third most common cancer among women (after breast and colon cancer).
Enter Merck, with "Gardasil" (and GlaxoSmithKline, in hot pursuit, with "Cervarix"). Gardasil has been shown to prevent 89 percent of infections caused by the four viral subtypes it covers: HPV 16, 18, 6 and 11. And Gardasil prevents 100 percent of the genital warts, the precancerous lesions, and the cervical cancers, that are caused by these four HPV subtypes. That means that Gardasil (and presumably Cervarix as well) can prevent 70 percent of all cervical cancers and over 95 percent of all invasive cervical cancers.
But, as fantastic as this is, 70 percent and 95 percent are obviously not 100 percent. Until something even more effective than Gardasil is developed, two tried and true preventive measures are essential to block that residual 30 percent: condoms and Pap tests.
It is true that condoms cannot provide complete protection against the spread of HPV, because HPV can infect genital areas not covered up by condoms. The HPV protection condoms do provide, however, is especially important for preventing internal infections?of cervical and rectal tissues. Condoms also, of course, offer very effective protection against the spread of HIV, chlamydia, and other STIs, and offer reasonably effective protection against unwanted pregnancies as well.
There are no blood tests to detect HPV infection. Pap tests remain the most effective way to screen women for cervical HPV. If evidence of HPV infection is found, then tests to sub-type the HPV can be undertaken. Here's why Pap tests are so important.
Cancer of the cervix and rectum are among the more treatable of cancers if they are caught early. In fact, early, microinvasive carcinomas of the cervix and anus are nearly always curable surgically. Both have a prolonged, pre-clinical phase, permitting this early detection and this very effective treatment. Most women diagnosed with invasive cervical cancer have not had a Pap smear in the previous five years. Many have never had one. Cervical cancer may indeed be an HPV-related "STD," as the OB-GYNs like to say, but, more importantly, it is a disease of medical neglect. The same is very much the case for anal cancer.
So, come into the health center for your Gardasil! You'll need three doses total (a second shot two months after the first, and a third four months later.) They have virtually no side-effects, other than the cost (right now, close to $150 per dose.) You won't need a pre-vaccination HPV screening or Pap test, and you don't need to be sexually active. Gardasil is recommended by the federal Centers for Disease Control for all girls and women between the ages of 9 and 26, and its efficacy and safety are currently under study in boys and men.
We are simply thrilled to be able to offer it to you!
Jeff Benson, M.D.
Dudley Coe Health Center