Nearly two decades ago, experts discovered a relationship between infection with HPV (human papillomavirus) and cervical cancer. Since then, these experts have learned much more about how HPV can lead to cervical cancer.
Here, what every woman and girl should know about this link.
Cervical cancer is cancer of the cervix, the narrow neck at the lower part of a woman's uterus, just above the vagina (Figure 1). It connects the uterus to the vagina.
Approximately eight out of 10 cervical cancers originate in surface cells lining the cervix (squamous cell carcinomas). These cancers do not form suddenly. Over time, healthy cervical cells can become abnormal in appearance -- this is called dysplasia. Although these cells are not cancerous, they can become cancer over time.
There are more than 100 types of HPV. About 30 or so types can cause genital infections. Some can cause genital warts; other types can cause cervical or other genital cancers. The other 70 or so HPV types can cause infections and warts elsewhere on the body, such as on the hands.
Many sexually active women and men will contract HPV at some point in their lifetime. Most will never even know it. Usually, this virus does not cause any symptoms and doesn't cause disease. Often, the body can clear HPV infection on its own within two years or less.
Some types of HPV, typically HPV 6 and HPV 11, cause genital warts. The warts are rarely associated with cervical cancers. They are considered "low-risk" HPV.
HPV and Cervical Cancer
Certain HPV types are classified as "high-risk" because they lead to abnormal cell changes and can cause genital cancers: cervical cancer as well as cancer of the vulva, anus, and penis. In fact, researchers say that virtually all cervical cancers -- more than 99% -- are caused by these high-risk HPV viruses. The most common of the high-risk strains of HPV are types 16 and 18, which cause about 70% of all cervical cancers.
If the body clears the infection, the cervical cells return to normal. But if the body doesn't clear the infection, the cells in the cervix can continue to change abnormally. This can lead to precancerous changes or cervical cancer.
Rates of Cervical Cancer
Actual cervical cancer is rare in the U.S. because most women get Pap tests and have abnormal cells treated before they turn into cancer. The American Cancer Society predicts that about 12,170 women will find out they have cervical cancer in the U.S. this year. They also say that roughly 4,220 women will die of the disease the same year.
How HPV Is Spread
HPV types associated with genital infections are transmitted sexually, primarily through skin-to-skin contact during sexual activity. HPV can also be spread through oral sex. The chance of getting HPV rises with certain risk factors:
Number of lifetime sexual partners (risk increases with more partners)
Young age: Women aged 20 to 24 are most likely to be infected, but they usually clear the HPV infection with no problems.
Women who are sexually active with men who have other partners at the same time.
Symptoms of High-Risk HPV Infection and Tests
When infection with high-risk HPV types occurs, there are usually no symptoms. Often, the first clue is a Pap test result that is abnormal. In a Pap test, the doctor takes a swab of cervical cells and has them analyzed in a laboratory. If the Pap test results are unclear, the doctor may order a HPV test to check the DNA type of the virus. This analysis can identify 13 or 14 of the high-risk HPV types associated with cervical cancer. It does not identify cancer. But it tells the woman and her doctor if she has a type of HPV capable of causing cancer.