|
One of the most important life-saving screening tests a woman can have is a routine Pap test.
The Pap test is simple, quick and painless. It can be done as part of a routine pelvic examination and is the single most effective cancer-screening test in medical history. Since the test was introduced after World War II, cervical cancer death rates have decreased 70 percent in the United States, according to the National Cancer Institute (NCI).
The test involves gathering a sampling of cells from the cervix and then examining them for abnormalities. During a pelvic exam, a speculum is inserted into the vagina to open it. The doctor then uses a swab to take cells from the cervix. In a conventional Pap smear, the cells are then spread onto a glass slide and sent to a laboratory for examination by a specially trained medical technologist, called a cytotechnologist.
The NCI estimates that thousands of women still fail to have routine Pap examinations. They may think they're finished having children and don't need them. They may think they're "too old" to have one. Unfortunately, of those women who die of cervical cancer, 80 percent have not had a Pap examination in five years or more.
Who needs a Pap test?
Women who are or have been sexually active or who have reached age 21 should have a Pap test routinely. The frequency recommended varies among specialty groups.
Risk factors for cervical cancer:
- Sex before age 20
- Multiple sexual partners (or male partners who have had multiple partners)
- Human papillomavirus
- Human immunodeficiency virus
- Smoking
The American College of Obstetrics and Gynecology (ACOG) recommends that all women should have an annual pelvic exam, but the frequency of Paps can vary.
- If you are under age 30 or have risk factors, you should get an annual Pap.
- If you are older than 30, but have had three negative (no disease) annual Paps in a row, you only need a Pap every two to three years.
- Even if you are postmenopausal, the ACOG recommends you get a Pap periodically.
- Women who have had hysterectomies should ask their doctor if they need a Pap test.
The United States Preventive Services Task Force (USPSTF) also recommends beginning Pap tests at age 21 or within three years of sexual activity, and recommends screening at least every three years. However, USPSTF recommends against routine Pap screening in women over age 65 who are not at risk for cervical cancer and have had normal Pap smears in the past. USPSTF also recommends against routine Pap smear screening in women who have had a total hysterectomy for benign disease.
More sensitive testing
Newer Pap test techniques have become available since 1930s when Dr. George Papanicolaou developed the Pap test, named for him. While no test is 100 percent accurate, the newer Pap technologies appear to be more sensitive for detecting abnormalities in cervical samples, according to Diane Solomon, M.D., a principal investigator at the NCI in Bethesda, MD. However, it is unclear whether the tests are primarily picking up more low-grade abnormalities that may not be a cause for alarm or more serious ones, she says.
"These tests are very promising, but they have not replaced the conventional Pap," Solomon says. "The new technology offers a range of screening options. Some provide greater sensitivity for detection of disease but often at an increased cost." The USPSTF has not gathered enough information yet to recommend for or against these new technologies for cervical cancer screening.
Tests approved by the Food and Drug Administration include:
The liquid-based cytology sample preparation (Cytyc Corporation's ThinPrep System, and Tripath Imaging Inc's AutoCyte PREP System ("PREP"): In these systems, instead of smearing cells on a slide, cells are rinsed into a liquid preparation and sent to a lab. The liquid-based test reduces debris and cell clumps. It also homogenizes the specimen.
"Imagine a cereal bowl with raisins," says Solomon. "If the raisins were clumped together and you stuck a spoon in the bowl, you might or might not come up with raisins. If you dispersed them evenly, your chance of coming up with raisins in a spoonful is more likely." The liquid-based technique, she says, is thus more likely to produce a representative sub-sampling.
Company claims for the increased sensitivity of these liquid-based tests over the conventional Pap test range from 65 percent to 157 percent.
Computer-assisted screening: Several automated systems using computer-generated images exist to re-screen Pap slides after an initial human inspection. However, an even newer technology, the AutoPap Primary Screening System (TriPath Imaging, Inc.), is now FDA-approved for screening prior to human inspection. The AutoPap System uses a high-speed video microscope, image interpretation software and specially designed field-of-view computers to image, analyze and classify cells within the Pap smear slide.
A Pap test should be done when a woman is not menstruating; the best time is between 10 and 20 days after the first day of the menstrual period, according to NCI. Its online CancerNet (cancernet.nci.nih.gov) provides answers to questions about Pap tests.
In addition to the Pap test, there is also a test that detects HPV (human papillomaviruses), which is a major risk factor for cervical cancer. Nearly all cervical cancers show evidence of HPV, although not all cases of HPV develop into cervical cancer, according to Solomon.
The HPV test is not an appropriate primary screening for all women, Solomon says. However, if a patient's Pap results indicate that the cells don't appear normal but it is unclear what is wrong with them, her physician may suggest HPV testing, according to Solomon. Another option, she says, would be to repeat the Pap smear in four to six months.
New vaccine
The Centers for Disease Control recommend that all girls who are 11 or 12 receive a new vaccine, called Gardasil® this vaccine blocks the virus that causes cervical cancer. The vaccine is also recommended for females ages 13 through 26 who have not received the vaccine series.
It is believed that the vaccine could cut worldwide deaths from the disease by two-thirds. It is still necessary for women to have regular cervical examinations and Pap tests.
|
Related Articles
|
|
External Source
 |
The National Cancer Institute
|
|
This article was reviewed and updated June 2007.
Return to the previous page
|
