The Pap test is quick, simple, inexpensive and minimally invasive. Moreover, it has cut the rate of cervical cancer deaths by 80%.
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Women have a secret weapon against cervical cancer. Actually it’s not so secret, but if women are willing to use it regularly, their safety against this former killer is virtually guaranteed.
The Pap smear has been around for half a century and during that time it’s cut the rate of cervical cancer deaths by up to 80 percent. It also has the advantage of being quick, relatively simple and minimally invasive.
It helps to understand what the Pap test is designed to accomplish. It’s a screening test, not a diagnostic test. As a result it has a reasonably high rate of both false positive and false negative results, meaning that many women will be referred for further screening for abnormal results, and suspicious findings may sometimes be missed.
But cervical cancer almost always develops very slowly over a period of 10 to 30 years. When the Pap test is repeated at regular intervals, every year for example, it becomes increasingly likely that any potential problems will be identified. When cervical cancer is found at the pre-cancerous stage, it’s known as dysplasia and dysplasia is 100 percent treatable, usually without need for a hysterectomy. Regular screening is the key to cancer detection.
The quality of the sample and how it is handled can also affect accuracy. The traditional Pap test uses a brush to collect cells from the wall of the cervix and then transfers those cells to a slide that is immediately fixed and sent to a lab for staining and analysis.
A newer method called the ThinPrep test also uses a soft brush to collect cells, but the cells are then rinsed into a fluid preservative in a vial which is sent to a lab.
A thin layer slide is made later by an automated slide processor. The thin layer technology, which is more expensive, is used by about half of all physician practices. It offers better cell preservation and eliminates confounding factors such as blood. Another plus is that if a test has an abnormal finding, there is enough material left to conduct a follow-up HPV test.
When a Test is Abnormal
Each year about 50 million American women have a Pap test. Most of them get an all clear, but about 2.5 million women are told that their findings are abnormal.
Most often an abnormal smear is classified as ASCUS (atypical squamous cells of undetermined significance). In other words something’s not right, but it’s not clear what’s causing the problem. Abnormal cells may be merely the result of inflammation that will resolve itself in a month or so or, less often, they may indicate a precancerous condition.
Women and their physicians have a number of options for follow up on an abnormal Pap test.
One option, given the fact that suspicious areas often resolve spontaneously, is to repeat the Pap test at 6 and 12 month intervals. Some women find the uncertainty and long-term worry associated with a prolonged wait difficult to deal with, although the risk that an abnormal Pap test will reveal a pre-cancerous condition is low, around 5 percent.
Abnormal cells may be merely the result of inflammation that will resolve itself; or they may indicate a precancerous condition.
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A second option, and one that provides a definitive diagnosis, is colposcopy, a more invasive and more expensive option. Colposcopy involves viewing the surface of the vagina and the cervix with a magnifying device to examine any suspicious areas and obtaining samples of any visible lesions that can then be sent for testing.
Colposcopy provides a more certain answer, but the procedure is uncomfortable and more invasive than a Pap test.
Another and much simpler option involves testing Pap smears for human papillomavirus (HPV). In recent years researchers have learned that HPV is implicated in the development of cervical cancer. In fact studies show that the virus is involved in 95 percent of cervical cancers.
Now that the connection between HPV and cervical cancer is clearly established, women need to take steps to protect themselves.
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There are many strains of HPV and several have a much higher risk of involvement with cancer. The HPV DNA test can be performed on the same sample taken for Pap testing.
If the HPV test is positive for a high risk strain of the virus, a physician can then schedule a colposcopy. If the HPV test is negative for these strains, a woman can be reassured that she is at low risk for cervical cancer and colposcopy is usually not needed.
New guidelines for physicians published in the Journal of the American Medical Association [April 24, 2002] state that after abnormal but inconclusive results of Pap testing, HPV testing is the preferred follow up step. Women with high risk strains can then be followed more closely.
Experts consider HPV testing as a second step a reasonable, intermediate testing strategy. A major advantage for women is that if the ThinPrep sample collection method has been used, the HPV test can be performed without the need of a second visit to collect a sample.
One study found that using HPV testing after abnormal Pap test findings resulted in 56 percent of women being referred for colposcopy, with 96 percent of cancerous lesions identified.
Now that the link between HPV infection and cervical cancer is clearly established, women need to take steps to protect themselves from infection.
Risk factors for HPV infection include a history of multiple sexual partners, sexual intercourse at an early age, first pregnancy at an early age, having a compromised immune system and smoking.
A major risk factor for cervical cancer is failure to get regular Pap smears. Each year 12,800 women in the United States are diagnosed with cervical cancer and 4,600 die as a result. The majority of deaths occur in women who were rarely, if ever, screened.
The Pap test is considered one of the most successful screening tests in the history of medicine. It’s essential that women use it as it’s meant to be used–at regular intervals as specified by their physician.
REFERENCES:
Ervin Blair et al, “ A New Era for the Pap Test,” JAAPA, December 2001.
Joyce Frieden, “FDA Advisory Panel Backs HPV Test as Pap Smear Adjunct,” Family Practice News, June 15, 2002.
“HPV Plus Pap Every 2 Years Can Add Years to Life, I Cost-Effective,” Women’s Health Weekly, May 30, 2002.
Timothy Kirn, “ASCUS Terms Simplified in Pap Smear System,” Internal Medicine News, December 15, 2001.
“Management of Women with Atypical Pap Tests of Undetermined Significance,” OB/GYN Clinical Alert, December 2001.
Joy Melnikow et al, “Management of the Low-Grade Abnormal Pap Smear: What Are Women’s Preferences?” Journal of Family Practice, October 2002.
“New Pap Test Guidelines Aim to Reduce Women’s Anxiety,” Cancer Weekly, May 21, 2002.
M. Norman Oliver, “HPV Testing Plus Pap Smear Every 2 Years Most Cost-Effective Cervical-Cancer Screen,” Journal of Family Practice, August 2002.
Carmen Steigman and John Vernick, “The Pap Smear: A Victim of Its Own Success,” Medical Laboratory Observer, August 2002.
Anne Walling, “Update on Controversy over Managing Abnormal Pap Smears,” American Family Physician, September 1, 2002.
Maryann Napoli, “How To Avoid Unnecessary Testing After Ambiguous Pap Test Results,” HealthFacts, May 2001.
