Medical Advances Likely to Reduce Threat of Cervical Cancer: Your Health
BY Rallie McAllister, M.D., MPH.
Most women can think of at least a thousand things they'd rather do than have their annual Pap test: sort laundry, vacuum, or even watch a couple of hours of televised sports. In spite of its lack of widespread appeal, there's no doubt that the test can be a lifesaver when it comes to preventing cancer of the cervix.
Less than a century ago, cervical cancer was the No. 1 cancer killer of U.S. women. Over the past 60 years, widespread use of the Pap test has helped cut the number of cervical cancer deaths by more than 70 percent.
The latest medical advances promise to further reduce the number of lives lost to cervical cancer. After decades of research, scientists recently identified the underlying cause of cervical cancer: certain types of the human papillomavirus, known as HPV.
Identification of the causative agent quickly led to the development of the first vaccine for HPV. In June 2006, the Advisory Committee on Immunization Practices (ACIP) voted to recommend the vaccine to protect against four HPV types, which together cause 70 percent of all cervical cancers.
According to obstetrician-gynecologist Thomas Herzog, M.D., Director of the Division of Gynecologic Oncology at Columbia University in New York, "The vaccine is safe, and does not cause HPV infection. Only the empty capsid, or the outer shell of the virus, is injected into the patient."
The vaccine is administered through a series of three injections over a six-month period. After vaccination, the immune system creates antibodies that protect women from acquiring an infection with the virus.
"It's important to understand that this vaccine doesn't protect against all forms of cervical cancer," Herzog noted. "In addition, we don't know how long the antibodies remain in the body, so we can't say with certainty exactly how long the vaccine remains protective."
For this reason, women who receive the HPV vaccine still need to schedule Paps on a regular basis. Fortunately, a relatively new version of the Pap smear, called the ThinPrep Pap Test, is significantly more effective in detecting precancerous and cancerous changes of the cervix than the older, traditional test.
Physicians have long known that original Pap smear, developed in 1943, isn't 100 percent foolproof. The test is associated with a rather high false negative rate, ranging from 20 to 40 percent.
The term "false negative" refers to a Pap smear that is interpreted as normal, when in fact precancerous or cancerous cells exist. Abnormal cells may go undetected when they aren't included in the specimen that is analyzed at a diagnostic laboratory.
When a physician or other clinician takes a small sample of cells from a patient's cervix to perform a traditional Pap test, the cells are immediately smeared onto a microscope slide. The specimen-containing slide is sent to a laboratory for evaluation, and the sample collection device is discarded. In some cases, more than 80 percent of the patient's sample remains on the discarded collection device.
While the discarded sample may contain only normal cells, there's a possibility that it might contain abnormal cells. It is the presence of abnormal cells that is critical to diagnosing cervical cancer, a condition that is highly treatable when caught in its early stages.
Using the traditional Pap smear, even the most skilled and conscientious clinicians have little control over which cells are transferred to the microscope slide for evaluation, and which cells are discarded. Clinicians using the ThinPrep Pap Test, on the other hand, capture virtually all of the cells in the sample when they rinse the collection device in a vial of preservative solution. At the laboratory, the contents of the vial are transferred to a microscope slide before being analyzed.
Because the newer version of the Pap test makes it easier to collect accurate specimens, false negative results occur less often, leading to fewer missed cases of cervical cancer. Based on this finding, the Food and Drug Administration approved the ThinPrep Pap Test as a replacement for the conventional Pap smear for cervical cancer screening.
In a clinical trial involving nearly 7,000 women, researchers found that the ThinPrep Pap Test increased the detection of abnormal cells in the cervix by 65 percent during routine screening. "Because the ThinPrep Pap Test is more sensitive than the conventional Pap smear, it reduces the number of unsatisfactory tests that need to be repeated," Herzog explained.
That's welcome news for every woman who can think of at least a thousand things she'd rather do.
Rallie McAllister, M.D., M.P.H., is a family physician in Kingsport, Tenn., and author of "Healthy Lunchbox: The Working Mom's Guide to Keeping You and Your Kids Trim."
COPYRIGHT 2006 CREATORS SYNDICATE, INC.
Categories: Health & Wellness
, Women's Health
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