Cervical cancer results from uncontrolled, untreated growth of abnormal cells in the cervix. Infection with a sexually transmitted virus, the human papillomavirus (HPV), causes such cells to develop and grow.
HPV is found on skin in the genital area and also in the tissues of the vagina, cervix, and mouth. It is primarily transmitted through skin- to-skin contact. Vaginal, anal, and oral sex also can spread HPV. Over 50 types of HPV can infect the cervix; 7 of them account for nearly all cervical cancers, with 2 types accounting for about 70% of cancers. Two other types of HPV cause most cases of genital warts.
An estimated 50% to 80% of sexually active women are infected with HPV at least once in their lives. In most cases the HPV infection clears on its own. In some women, however, HPV persists and causes precancerous growths, which can develop into cancer. Overall, less than 5% of women with persistent HPV infection get cervical cancer.
Cancer of the cervix usually takes 10 to 20 years or more to develop, and so there is a long period of opportunity to detect and treat changes and precancerous growths before they become cancer. This is the goal of cervical cancer screening.
Some factors make women more likely to be infected by HPV. Other factors make infection with the most risky types of HPV progress to cervical cancer more quickly. A woman with any of these characteristics would benefit especially from screening:
Screening and Treatment
Screening for cervical cancer is simple, quick, and generally not painful. Women age 30 years and older and women of any age living with HIV should be screened for cervical cancer. The screening should be repeated every 3 to 5 years. Any precancerous cervical changes that are detected can be treated successfully.
Three screening methods are recommended, depending on the capacity and conditions in a region. These methods are HPV testing, cytology (Papanicolaou, or Pap) screening, and/or visual inspection with acetic acid (VIA). The first 2 methods involve scraping a small sample of cells from the cervix. VIA involves looking at the cervix after it is coated with a weak vinegar solution. All three methods generally require a woman to go to a facility for testing (although HPV testing can use self-collected vaginal samples). Then she may have to return for the test results. VIA and some HPV tests can provide results at the first visit, and any preventive treatment needed can be offered at the same visit.
If a test finds precancerous changes, they must be treated to prevent progression to cancer. These changes can be removed by freezing with a probe (cryotherapy) or cut away using a hot wire loop (loop electrosurgical excision procedure [LEEP]). Freezing is less effective for larger growths, but LEEP requires electricity and more extensive training. No hospital stay is needed for either type of treatment. Both treatments are generally well-tolerated and effective.
Treatment for cervical cancer includes surgery or radiation therapy, sometimes together with chemotherapy. Treatment can be effective if the cancer is detected early. Women with advanced cervical cancer, however, have a high mortality rate.
Vaccine Available for Prevention
In the mid 2000s the European Union and the United States Food and Drug Administration approved 2 vaccines against cervical cancer, precancer, and genital warts. One vaccine, called Gardasil, protects against infection by 4 types of HPV that account for about 70% of all cervical cancers and an estimated 90% of all genital warts. The other vaccine, Cervarix, protects against the 2 main cancer-causing HPV types. Both vaccines are most effective when administered to girls before they become sexually active. They are available through GAVI—the Global Alliance for Vaccines and Immunization—and they are offered by programs around the world. A new vaccine protecting against 9 HPV types, which will protect against the great majority of cervical cancers, has recently been approved and will likely become available globally in 2018.