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What Is Cervical Cancer?

The cervix is 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 8 out of 10 cervical cancers originate in surface cells lining the cervix (squamous cell carcinomas). These cancers do not form suddenly. In some women, healthy cervical cells become abnormal in appearance — this is called dysplasia. Although these cells are not cancerous, they can become so.

When dysplastic cells turn cancerous (malignant), the first detectable stage is carcinoma in situ (CIS). 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.

Just 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 smear — a highly effective, widely available screening test in the United States — cervical cancer is one of the least threatening forms of cancer and usually easily diagnosed at early stages. When caught early, it is curable. Even in advanced cases, the chance of surviving at least five years, with likelihood of 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 a lower chance of survival.

The American Cancer Society estimates that in 2005, about 10,370 cases of invasive cervical cancer will be diagnosed in the U.S. 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 smear 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. It is estimated that in 2005, an estimated 3,710 women will die from the disease. In other countries where Pap smears are not used regularly, it is still a common cause of death.

Dysplasia is most likely to occur in women between the ages of 25 and 35, carcinoma in situ between ages 30 and 40, and invasive cancer between ages 40 and 60. Cervical cancer constitutes about 2%- 2.5% of all cancers deaths afflicting American women. Each year about 55,000 cases of carcinoma in situ and about 15,000 cases of invasive cancer are diagnosed.

What Causes It?

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 papilloma virus. It’s believed that this virus interferes with the functioning of substances that keep cervical cells from growing out of control and becoming cancerous.

There are more than 100 different types of HPV. The ones most people have heard of 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. The genital HPVs are passed from one person to another during skin to skin sexual contact. Most women with genital HPV do not develop cervical cancer because their immune system can fight the virus. HPV infection can cause changes in the cells which then can be picked up on a Pap smear. 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 smear, doctors are more inclined to 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
• Having many sexual partners
• Having unprotected sex

Chlamydia infection. Chlamydia is a common sexually transmitted infection of the reproductive tract. It may or may not cause symptoms. This infection can be detected during your pelvic examination and Pap smear. Recent studies have found that women whose blood test show past or current chlamydia infection are at higher risk for cervical cancer than those who test negative.

Heredity. Apparently, genetic makeup and other factors are also part of the complex interactions that cause cervical cancer. Studies suggest that women whose mother or sisters have had cervical cancer are more likely to develop the disease themselves.

Smoking. Cervical cancer is also more common among women who smoke. It has been debated whether smoking causes cervical cancer on its own but believe that it may heighten one's vulnerability to other illnesses, such as viral infections. Researchers have found substances from tobacco in the cervical mucus of smokers. These substances may be toxic to the cells of the cervix and contribute to the development of cervical cancer.

Other. Women whose immune system is severely suppressed by other diseases, by treatments, or by organ transplants are more vulnerable to cervical cancer, as are women whose mothers took diethylstilbestrol (DES) while pregnant (DES is a drug once prescribed to prevent miscarriage but is no longer marketed). Women who are obese or who use birth-control pills may be at slightly increased risk.

Age. Cervical cancer is most common in women between the ages of 50 and 55 and almost never occurs in girls younger than 15. The message: Get regular Pap smears as soon as you become sexually active or starting at age 18 and continue until you are at least 70, if not longer.

Human immunodeficiency virus (HIV) infection. Infection with the AIDS virus makes women susceptible to cervical cancer because the infection damages the immune system’s ability to destroy cancer cells early. In women infected with HIV, the usual slow progression from a precancer to cancer state might be faster than it normal.

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