 | | | | Medical Health Encyclopedia | | Reliability and Accuracy. Over the course of a lifetime of regular screening, a woman faces a 40% chance of being told her Pap smear is abnormal. The Pap smear is not, however, a perfectly reliable measure of a woman's risk for cervical cancer. In general, about 10% of Pap smears have abnormal results, but only about 0.1% of the women who have these results actually have cancer. In most cases, abnormal cells are low grade and not likely to progress to cancer or are due to benign conditions, including natural cell changes after menopause. No test is 100% accurate, and it is possible for the Pap smear to miss the presence of cancer. However, it should be noted that if abnormal cells are missed on one test they are likely to be spotted during the next one without a significant danger. Liquid-Based Pap TestText Continues Below
Newer, thin-layer liquid based tests (ThinPrep, SurePath) use the original cervical sample, which is rinsed in a special solution to thin the mucus (rather then dried). The result is a clear, clean sample that may be able to accurately reveal abnormal cell. The fluid can also be examined for evidence of HPV and other early abnormalities. Some--but not all--studies have found this test to be more accurate than the standard Pap smear. Current Pap Smear Screening Recommendations
The US Preventive Service Task Force (USPST), the American Cancer Society (ACS), and the American College of Obstetricians and Gynecologists (ACOG) have all released guidelines for cervical cancer screening. ACOG and ACS have established separate screening criteria for women below and above 30 years of age. Although there are some small differences between these three sets of guidelines, they generally make similar recommendations as summarized below:
Recommendations for Initial Screening. Women should begin to undergo Pap tests within three years of onset of sexual activity or at age 21 (whichever comes first).
Note: Women with no history of sexual activity should still have Pap smears. They are at low risk for squamous cell carcinoma, but adenocarcinoma (cancer that occurs in cervical glands) can occur, although this is very uncommon.
Women Up to Age 30. Women under age 30 should receive annual screening with the conventional Pap smear. The American Cancer Society (ACS) offers the alternative of screening every 2 years using the newer liquid-based testing. HPV testing is not recommended for this age group because HPV infections in women under age 30 tend to resolve on their own.
Women Age 30 and Over. Women in this age group who have received three consecutive negative (normal) annual Pap tests have two screening options:
- Screening with standard or liquid-based Pap tests every 2-3 years. Women in high-risk groups (DES exposure, HIV infection, weakened immune system, or previous diagnosis of cervical cancer) should continue to receive annual tests.
- Screening with Pap test plus HPV DNA test. If a woman tests negative on both of these tests, then she can be rescreened no more frequently than once every 3 years. If one of the tests if positive, she will need to be screened more frequently.
Elderly Women. In its 2003 guidelines, US Preventive Service Task Force recommends against routine screening in women over age 65 with low or no risk factors. (The ACS recommends stopping at age 70 and ACOG declines to set an upper age limit.) Such women have had at least three previous normal screenings and have had no abnormal results for at least 10 years. Older women should be screened if they have not been screened before or if there is a possibility that they have not been screened (for example, the woman is from a country that does not do routine screening.)
After a Hysterectomy. The 2003 guidelines recommend against routine screening for women who have undergone a total hysterectomy for benign causes. Women who have had a hysterectomy that preserves the cervix (called a supracervical hysterectomy) should continue with Pap screening.
Follow-up After Normal Results
If Pap smear results are normal for three consecutive years, most expert groups recommend a Pap test every 2 to 3 years thereafter in most women over 30 years of age. (The ACS suggests that such women wait until they are 30 before extending the interval to three years.)
Both the ACS and the American College of Obstetricians and Gynecologists (ACOG) recommend that annual screening should continue in women in high-risk categories. High risk categories may include the following, depending on the medical group:
- Women who have had multiple sexual partners or whose male sexual partners have had multiple partners.
- Women who engaged in sexual activity at a young age.
- Women whose male sexual partners have had other sexual partners with cervical cancer.
- Women with current or prior HPV infection.
- Women who are HIV-positive or who are immunosuppressed.
- Women with a history of sexually transmitted diseases.
- Smokers and substance or drug abusers.
- Women who have a history of cervical dysplasia or cervical cancer or endometrial, vaginal, or vulvar cancer.
- Women in lower socioeconomic groups, particularly if they have not been able to obtain regular gynecologic screening and care.
Follow-up After Abnormal Results
Any abnormal result, even a mild abnormality, requires follow-up visits and additional tests. The extent of these tests depends on the degree of abnormalities.
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