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Pap Tests: Starting Point for a Cervical Cancer Diagnosis

Irregularities found in a Pap smear could lead to more testing

Second Opinion

The purpose of a Pap smear, the most reliable test to date for cervical cancer, is to sample the squamous cells of the cervix, looking for any abnormalities.

It is also important to know that a Pap smear is not a test for ovarian or endometrial cancers (cancer of the uterus).

A Pap smear (also called a Pap test) is usually given as part of a pelvic exam. It is a screening test in which cells collected from the cervix are examined for abnormal cell changes that may indicate the presence of cervical cancer or a precancerous condition. If abnormalities are found, your doctor may order diagnostic exams to identify the cause.

The importance of having Pap tests on a routine basis cannot be overstated. Most invasive cervical cancers can be prevented if you have Pap tests regularly. That is because they can detect squamous cell abnormalities that may lead to cervical cancer at their earliest stages. Early detection enables doctors to start you on a treatment before cancer develops, which increases the likelihood that your treatment will be successful.

Like all screening tests, the Pap test is not 100 percent accurate. Many factors can interfere with accuracy and can lead to false positive and false negative results. Newer testing methods, including liquid-based Pap tests, may improve sensitivity. But until a foolproof test is developed, having Pap tests on a regular basis increases the likelihood that any problems will be detected over time, from one exam to the next.

How often should you have a Pap test? That depends on what your doctor recommends, your age and other factors. But conventional practice has changed in the past couple of years, and some women may not need a Pap test every year. For more information, see the revised cervical cancer screening guidelines issued by the American College of Obstetricians and Gynecologists.

Preparing for a Pap test. You should have this test when you are not menstruating; the best time is between 10 and 20 days after the first day of your menstrual period. For about two days prior to the test, do not douche or use vaginal creams, spermicidal foams or jellies. Do not have intercourse within 24 hours before the Pap smear because it can cause inaccurate test results.

How the test is done. The Pap test is a quick and painless procedure which involves taking a small sample of cells from the cervix, usually during a routine pelvic exam. The cells are sent to a laboratory where they are prepared and evaluated under a microscope by a cytotechnologist, who is looking for any abnormal features associated with cancerous or precancerous cervical cells.

What the results mean. In reporting Pap results to your physician, the laboratory uses a set of standard terms called the Bethesda System. These terms are described in the chart below along with additional tests and treatments your doctor may order to gather more information about a particular result.

If your doctor tells you that your Pap test results are "abnormal," it is not necessarily cause for alarm. Cells on the surface of the cervix sometimes appear abnormal but are very rarely cancerous. Also keep in mind that abnormal cells do not always become cancerous. If you get an abnormal result, ask your doctor for specific information about what the result means.

Be aware that false positive and false negative results can happen. If one of these results comes back from your Pap test, you will save yourself a lot of worry and confusion if you know what these terms mean:

  • False positive: You are told that you have abnormal cells when, in fact, the cells are normal. A false positive means that there is no problem.
  • False negative: You are informed that your cells are normal when an abnormal change has actually taken place. This means you could have a problem and there may be a need for more tests.

Pap Test Results

WNL Within normal limits — the cells are of healthy size and shape. A negative result.

Follow-up tests/treatments may include:

  • No special procedures needed.
  • Continue routine Pap tests.

ASCUS Atypical squamous cells of undetermined significance. The squamous cells do not appear completely normal, but doctors are uncertain about what the cell changes mean. Sometimes the changes are related to HPV infection. Considered mild cell abnormalities.

Follow-up tests/treatments may include:

  • HPV testing.
  • Repeat Pap test.
  • Colposcopy and biopsy.
  • Estrogen cream.

ASC-H Atypical squamous cells cannot exclude a high-grade squamous intraepithelial lesion. The cells do not appear normal, but doctors are uncertain about what the cell changes mean. ASC-H may be at higher risk of being precancerous.

Follow-up tests/treatments may include:

  • Colposcopy and biopsy.

AGC Atypical glandular cells. Glandular cells are mucus-producing cells found in the endocervical canal (opening in the center of the cervix) or in the lining of the uterus. The cells do not appear normal, but doctors are uncertain about what the cell changes mean.

Follow-up tests/treatments may include:

  • Colposcopy and biopsy and/or endocervical curettage.

AIS Endocervical adenocarcinoma in situ. Precancerous cells are found in the glandular tissue.

Follow-up tests/treatments may include:

  • Colposcopy and biopsy and/or endocervical curettage.

LSIL Low-grade squamous intraepithelial lesion. Low-grade means there are early changes in the size and shape of cells. "Lesion" refers to an area of abnormal tissue. Intraepithelial is the layer of cells that forms the surface of the cervix. LSILs are considered mild abnormalities caused by HPV infection.

Follow-up tests/treatments may include:

  • Colposcopy and biopsy.

HSIL High-grade squamous intraepithelial lesion. High-grade means that there are more marked changes in the size and shape of the abnormal (precancerous) cells. This means the cells look very different from normal cells. HSILs are more severe abnormalities and have a higher likelihood of progressing to invasive cancer.

Follow-up tests/treatments may include:

  • Colposcopy and biopsy and/or endocervical curettage.
  • Further treatment with LEEP, cryotherapy, laser therapy, conization or hysterectomy.

HPV and the Link to Cervical Cancer
HPV is a virus that is associated with cervical cancer. If you do not have HPV, you will not have cervical cancer.

Even if you do have HPV, it is important to know what kind you have, because only a few viruses cause cancer. Most women with cancer-associated HPVs will not get cervical cancer.

HPV, or human papillomavirus, is one of the most widespread sexually transmitted diseases in the United States. It's also the infection responsible for causing nearly all cases of cervical cancer.

HPV is not a single virus. As many as 100 different types have been isolated by scientists. About 30 HPV strains can infect the genital areas and may cause genital warts. Among the genital strains, 13 types of HPV pose a high risk of triggering cell changes on the cervix that can progress into cervical cancer. Approximately 70 percent of all cervical cancers are associated with two of the high-risk types of HPV (HPV 16 and 18).

Because HPV usually causes no symptoms, you can have it and not even know it. Some studies suggest that the majority of sexually active men and women in the United States have been infected with at least one type of HPV in their lifetimes. As common as HPV is, it is important to note that:

  • If you do not have HPV, you will not get cervical cancer.
  • Not all types of HPV cause cervical cancer.
  • Having HPV does not necessarily mean you will get cervical cancer. In most women, the body's immune system renders the virus harmless.
  • Even if you do have a high-risk strain of HPV, early detection and treatment can eliminate the threat before the virus causes harm.
  • Women who have never been sexually active are unlikely to get HPV and have a very low risk for developing cervical cancer.

Sexual behavior is the most critical risk factor for getting HPV. So, if you are sexually active, be aware that:

  • HPV spreads through skin-to-skin contact, not by bodily fluids.
  • Using condoms cannot entirely protect you against HPV.
  • Women with multiple sex partners have a much greater risk of being infected than women who are monogamous.
  • Anyone with a suppressed immune system is at greater risk of being infected with HPV.
  • HPV can be contracted from one partner and go dormant for extended periods of time. It can then become active enough to be transmitted to another sexual partner, even a spouse.
  • In a small number of women, the virus can live dormant for years and eventually convert cells on the cervix into cancer cells.

Testing for HPV

There is a test — just as quick, simple and painless as the Pap test — which  can determine whether you have any of the high-risk types of HPV before there are any conclusive visible changes to the cervical cells. It is called the HPV-DNA test, and it was approved by the Food and Drug Administration in 2000 to determine whether women with abnormal Pap tests needed further examination or testing.

In 2003, the FDA approved the expanded use of the test. It can now be done routinely, in conjunction with a Pap smear, to screen women over the age of 30 for HPV infection. Results of the Pap and HPV-DNA tests, together with a complete medical history and evaluation of other risk factors, can help physicians determine what sort of follow-up treatment may be necessary.

Like the Pap test, the HPV-DNA test is performed by collecting cells from the cervix (usually at the same time a Pap test sample is taken) then sending them to a laboratory for analysis.

The HPV-DNA test is not approved by the FDA as a substitute for regular Pap screening, nor is it intended to screen women under 30 who have normal Pap tests.
Schedule Annual Exams

It is important to continue to reassess your gynecological health. Even when vaccines are made available for prevention and treatment of HPV, annual physical exams and cytology will remain critical for a woman's ongoing health care.

Biotechnology firms, pharmaceutical companies and academic researchers are continuing their work to develop vaccines against the types of HPV that cause cervical cancer. Some are designing vaccines to prevent initial HPV infections which, if successful, hold the promise of eliminating cervical cancer entirely. Others are focusing on vaccines to control the progress of cancer or prevent its recurrence in women who already have cervical dysplasia or cancer.

While a number of these vaccines are in clinical trials, developers still face many challenges, and it may be years before an effective and affordable vaccine will be available for widespread use.

In the meantime, regular pelvic exams, including cervical cancer screening, are your best protection against the disease. While you should consult with your doctor to find out how often you should be screened, recently revised guidelines for cervical cancer screening from the American College of Obstetricians and Gynecologists (ACOG) provide the following specific recommendations.

First screen Women up to age 30 Women age 30 and older
About three years after first sexual intercourse or by age 21, whichever comes first. Annual cervical cytology (Pap) testing. Three screening options:
  1. Women who have had three negative results on annual Pap tests can be re-screened with cytology alone every two to three years.
  2. Annual cervical cytology testing.
  3. Cytology with the addition of an HPV-DNA test. If both the cervical cytology and the DNA test are negative, re-screening should occur no sooner than three years.

*Women of any age who are immunocompromised, are infected with HIV or were exposed in utero to DES should be screened annually.

Source: American College of Obstetricians and Gynecologists

The American College of Obstetricians and Gynecologists also noted in its guidelines that most women who have had a hysterectomy with removal of the cervix for benign reasons may discontinue routine Pap testing. However, women who have had the procedure and also have a history of abnormal cell growth should be screened annually until they have had three consecutive, negative Pap tests, at which time they can discontinue routine screening.

Other generally accepted screening guidelines call for:

  • Post-menopausal women to continue to have regular Pap tests.
  • Women 65 to 70 who have had at least three normal Pap tests and no abnormal Pap tests in the last 10 years may decide, after talking with their physicians, to stop having Pap tests.

This article reprinted with permission from Second Opinion, a public television health program hosted by Dr. Peter Salgo and produced by WXXI (Rochester, N.Y.),  West 175 and the University of Rochester Medical Center.

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