Pap Smear Can Spot Cancer in Curable Stage

Since 1950, the number of women in the United States dying of cancer of the cervix has decreased more than 75%. In spite of this progress, nearly 5,000 American women still die each year from cervical cancer, and in up to 90% of these women it is because they are not getting Pap smears when they should.

A Pap smear is obtained during a pelvic exam by gently scraping cells off the surface of the cervix for examination under a microscope. This simple test makes it possible to identify precancerous changes in the cervical cells so treatment can be initiated before cancer develops.

Cervical cancer usually develops very slowly and typically goes through a precancerous stage, called dysplasia. During this stage, the cervical cells resemble cancer cells under a microscope but do not behave like cancer cells.

If dysplasia is detected, treatments can prevent the progression to cancer. Even if cancer has developed, it can be treated more effectively if it is detected early. When cervical cancer is treated before the tumor has invaded deeply into healthy tissues, the chance of a cure is greater than 90%. Once the cancer has gone beyond this point, spreading to nearby lymph nodes, the uterus or other organs, the cure rate drops dramatically.

Because dysplasia rarely causes any symptoms, and the precancerous changes on the cervix may not be apparent to the doctor during a pelvic examination, regular screening with Pap smears is essential.

The American Cancer Society recommends annual Pap tests for all women who have ever been sexually active, regardless of their age. If a woman has been sexually inactive, annual Pap smears are advised from age 18 onward. Although the benefit of Pap smears after age 65 is less clear than in younger women, the American Cancer Society feels that they should not be discontinued in older women. (In fact, most cases of invasive cervical cancer are diagnosed in older women.)

If a woman has three consecutive normal Pap smears and she is at low risk for cervical cancer, she may be advised to decrease the frequency of testing to once every two to three years.

Annual testing is usually continued for women with a high risk of cervical cancer because of one or more of the following risk factors: human papilloma virus infection, early age at first intercourse, multiple sexual partners, a history of smoking and a weakened immune system.

HPV infection: More than 90% of women who develop cancer of the cervix have been infected with the human papilloma virus, or HPV. It is estimated that more than 6 million women in the United States are infected with the virus, the result of sexual intercourse with an infected partner. Many of these women are not aware they have been infected because the virus usually does not cause any symptoms. Although HPV infection increases cervical cancer risk, not all infected women develop it. It appears that there are more than 70 types of human papilloma virus, and only a few of them are strongly associated with cancer. Although specialized testing can differentiate one virus type from another, it is not widely performed or recommended.

Sexual history: Women have an increased risk of cervical cancer if they have had many sexual partners or if they began having sexual intercourse before age 17 (probably because they were more likely to be exposed to sexually transmitted diseases, particularly human papilloma virus). A woman whose sexual partner has had multiple sexual partners is also at increased risk.

Smoking: The more cigarettes a woman smokes, and the more years she has been smoking, the greater her risk. Even nonsmoking women who have been exposed to secondhand tobacco smoke are at increased risk.

Weakened immune system: Women infected with the human immunodeficiency virus and women who take immuno-suppressive medications develop cancer at an increased rate. Low levels of carotinoids, such as beta-carotene, in the diet have also been associated with a higher risk of cervical cancer. Because the ideal interval for Pap smears varies with a woman’s individual risk for cervical cancer, this is a subject that every woman should discuss with her physician. This discussion will enable the doctor to recommend the optimal cervical screening program for each woman.

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Dr. Jonathan Fielding is the director of public health and the health officer for the Los Angeles County Department of Health Services. Valerie Ulene is a board-certified specialist in preventive medicine practicing in Los Angeles. They can be reached by e-mail at ourhealth@dhs.co.la.ca.us. Our Health is published the second and fourth Mondays of each month.