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Each year 3.5 million women have some degree of abnormality on their Pap smear the test most commonly used to screen for cervical cancer and require additional attention. But until 2001 there were no national guidelines on the best way for clinicians to treat these women.
The American Society of Colposcopy and Cervical Pathology brought together experts in cervical cancer prevention to develop comprehensive specifications. The guidelines they created could make things easier for women who have inconclusive Pap smear results.
The most common abnormal Pap smear result, occurring in about 1 in 20 tests, is called atypical squamous cells of undetermined significance (ASC-US). While most women with ASC-US do not have a significant cervical lesion and only about 1 in 1,000 have cervical cancer, they are at considerable risk for a high-grade cervical cancer precursor lesion and require some form of follow-up.
The conference evaluated data supporting different approaches of ASC-US management and found that three are safe and effective: repeating the Pap test at least twice over an 8-12 month period, inspecting the cervix with a colposcope and obtaining cervical biopsies, and testing for human papillomavirus (HPV), a sexually transmitted disease that causes genital warts and is linked to most cases of cervical cancer.
According to the Consensus Conference judgment, women with abnormal Pap tests that are not ASC-US need to undergo a colposcopic examination (inspection of the cervix using a microscopy) and cervical biopsies.
The guidelines also tout a relatively new technique, liquid-based cervical cytology, in which cervical cells are collected in liquid instead of smeared onto a slide, as in a Pap smear. The liquid-based screening makes more cells available if additional HPV testing is needed, which means women would only need to have one sample taken.
The complete set of guidelines can be found in the April 24, 2002, issue of the Journal of the American Medical Association.
June 2002 Update
Most women know that regular Pap smears can almost eliminate the chances of developing invasive cervical cancer. By examining the cervix for abnormal (and potentially precancerous) cells, treatment can be started before a real problem develops.
What many women may not know is that human papilloma viruses (HPVs) (which cause genital warts) are responsible for the majority of cases of cervical cancer. Two recent studies suggest that regular screening for HPV may prove even more effective than the traditional Pap smear in preventing cervical cancer.
The first study included 8,554 women who lived in the Gaunacaste Province of Costa Rica, where there is a very high rate of cervical cancer. Researchers found that HPV testing picked up 17% more high-grade cervical cell abormalities and cancers.
The second study compared the Pap smear with testing vaginal samples for HPV. 1,415 women in South Africa (who had not had any cervical cancer screening) participated. The first HPV test was done by a doctor during a routine physical exam. The HPV test was done on samples of vaginal fluid the women collected themselves using a cotton swab. All the women had Pap smears done as well. The HPV testing on samples taken by the doctor detected far more cervical disease than the Pap smear (84% vs. 68%). The HPV testing done on the self-collected samples was not equivalent to the HPV tests done on the physician-collected samples, but was just as good as the Pap smear. And did not require a trip to the doctors office.
What are the important take-home messages from these studies? First, each year in the United States there are an estimated 15,000 new cases of cervical cancer. Each year, about 5,000 women will die needlessly of the disease. Regular Pap smears are the most effective way to screen for this disease. Second, although HPV is one of the most common sexually transmitted infections, only a small number of women suffer complications, including cervical disease. There are over 70 types of HPV, but only 13 are known to cause cervical cancer.
Still, screening techniques that include HPV testing may not only increase the ability to detect abnormal cell changes early, but can also let a woman know whether or not she carries one of the more dangerous viruses (and therefore needs to be extra vigilant about screening). Finally, self-collected samples for testing may take us a big step forward in preventing this disease in places where women do not get regular visits to the doctor.