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.
When dysplastic cells become cancerous (malignant), the first detectable stage is carcinoma in situ (CIS) -- a non-invasive cervical cancer. As cancer cells multiply, some may invade the lining of the cervix itself, spread to nearby tissue, and enter the bloodstream or lymphatic system and spread to other parts of the body.
As it usually takes many years for dysplasia to become carcinoma in situ, it often takes months or even years for cervical cancer to become invasive. (In women with HIV this progression may be faster.) Because of the usual slow progression and because of the Pap test -- a highly effective, widely available screening test in the U.S. -- cervical cancer is one of the least threatening forms of cancer and usually easily diagnosed at precancerous stages.
When caught early, it is curable. Even with advanced stages included, the overall chance of surviving at least five years, with likelihood of a full cure, is still better than 70%. Only when the cancer spreads to distant organs does prognosis for five-year survival dip below 20%. Recurrent cervical cancer carries an even lower chance of survival.
The American Cancer Society estimates that about 12,710 cases of invasive cervical cancer will be diagnosed in the U.S., and approximately 4,290 women will die of this cancer each year. Noninvasive cervical cancers are more common; it’s estimated that they are four times more common than invasive disease.
The rates of death from cervical cancer continue to decline. Between the mid 1950s and the mid 1990s, the rate declined by 74%. That's mostly due to the use of the Pap test for providing a way to sample the cells on the surface of the cervix and detect early abnormal changes. The rate continues to decline today by about 4% a year. In other countries where Pap tests are not used regularly, it is a more common cause of death.
Doctors are getting closer to understanding the underlying causes of cervical cancer and have identified a number of factors that put you at higher risk for developing the disease.
HPV. The most important risk factor for cervical cancer is infection with the sexually transmitted infection called human papillomavirus.
There are more than 100 different types of HPV, of which 40 infect the genital tract. Some types of HPV cause genital warts. Other types cause warts elsewhere on the body. Only certain types of HPV increase cervical cancer risk. They are called “high-risk” types of HPV. They include types 16, 18, 31, 33, and 45, and others. Genital HPV is passed from one person to another during skin to skin sexual contact. Most people who are infected with HPV clear the virus on their own and will not develop cervical cancer. HPV infection can cause changes in the cervical cells which then can be picked up on a Pap test. Recently, some doctors have started testing for HPV at the time of a Pap. If a high-risk type of HPV is found in women with an abnormal Pap test, doctors may do a colposcopy (look at the cervix directly with a specialized microscope). What puts you at risk of HPV infection?
Having intercourse at an early age, especially if before 18 years of age or within one year of the start of your period