Screening for Cervical cancer

August 2, 2011

Cancer of the cervix is the most common cancer of the reproductive organs after endometrial and ovarian cancers. Nearly 13,000 new cases of cervical cancer are diagnosed every year in the United States, with over 4,000 deaths attributed to this illness. Pap smears have resulted in significant reductions in deaths due to cervical cancer. Interestingly, the incidence of cervical cancer is increasing in younger women. For example, in 1981, women less than 50 years of age accounted for 21% of all the deaths. By 1997, women under the age of 50 accounted for almost 44% of all the deaths. This increase is felt to be a result of an early onset of sexual activity.

Cervical cancer begins in the lining of the cervix, which is the lower part of the uterus. It develops over many years. The first stage of development is called dysplasia. Dysplasia is defined by the cellular change that occurs when the cells go from the normal state to the precancerous state. This occurs most often in women in their late 20s and early 30s. These precancerous changes can resolve without treatment or they may progress into the next phase, which is called carcinoma in situ. From this phase, the cancer cells may spread locally to nearby tissues or can enter the bloodstream or the lymph glands and travel to other organs. This more advanced form of cervical cancer is found in women generally older than the age of 40.

Several of the risks related to cervical cancer are related to sexual activity and include multiple sexual partners, early onset of intercourse, and infection with the human papillomavirus (HPV). Smoking increases the risk of dysplasia. Low socioeconomic status is another risk factor. Women infected with HIV have a higher incidence of HPV infection and their lesions are more aggressive. In fact, cervical cancer in a woman with HIV is an AIDS-defining illness.

HPV DNA can be found in more than 90% of all cervical cancers. Women who are infected with HPV before the age of 25 are 40 times more likely to develop cervical cancer than those who are not infected.

Cervical cancer screening is performed by means of Pap smears. A screening Pap smear should be done under optimal circumstances. Specifically, the Pap smear should not be obtained if a woman has douched, used any vaginal medications, or inserted a tampon within the previous 24 hours. Cells can be inadvertently removed as a result and yield a falsely negative interpretation. The health care provider uses a speculum to perform this test. The cervix is located and a cervical spatula is placed firmly against the cervix and swept around 360°. The purpose is to recover the cervical cells from within a certain area of the cervix called the endocervix. There are specific methods of preserving the cells once they are placed on the slide. The U.S. Preventive Services Task Force (USPSTF, which is an independent group of experts that weighs the evidence for making clinical decisions) found poor evidence to determine whether or not the newer technologies, such as liquid cytology or computerized screening, are more effective than the conventional Pap smear in reducing death from cervical cancer. These methods are new and are commonly used. However, it is important to note that the task force found the evidence insufficient to recommend for or against the routine use of these newer technologies.

As is common in medicine, controversy does exist with regard to how frequently women should be screened for cancer, at what age they should be screened, and what should be done to follow up the abnormal tests. As reported in the media, there can be a falsenegative reading of 10-30% on Pap smears. This means that they may be reported as normal when an abnormality does exist.

In 2003, the USPSTF presented an update of recommendations for screening for cervical cancer. The task force found good evidence from multiple studies that screening does reduce the incidence and deaths from cervical cancer. Evidence suggests that the benefit can be obtained by beginning the screening within 3 years of onset of sexual activity or the age of 21, whichever comes first. The screening should take place at least every 3 years.

The task force recommends against routinely screening women older than the age of 65 if they have had adequate recent screening with normal Pap smears and have no other risk factors for cervical cancer. It is important to emphasize that these particular women have had adequate recent screening. Women who have not had adequate screening with Pap smears should have regular screening at an interval to be decided in conjunction with her health care provider.

The USPSTF recommends against routine Pap smear screening in women who have had a total hysterectomy for a noncancerous disease. At the present time, the USPSTF concludes that there is insufficient evidence to recommend for or against the routine use of HPV testing as a primary screening test for cervical cancer.

The management of abnormal Pap smears is based on many factors. Up to 50% of patients have spontaneous resolution of borderline and low-grade lesions and do not require more invasive procedures. However, 20-50% of women with low-grade lesions have a more advanced lesion seen on colposcopy. Colposcopy is a procedure performed during the pelvic examination that uses an instrument similar to a microscope. It magnifies the cervix 8-10 times and allows for better visualization of the cervix, vagina, and vulva. The follow-up of abnormal lesions is based on many factors including history of prior positive Pap smears, HPV exposure, compliance with medical treatment, and sexual history. Women who are deemed to be at high risk may require more aggressive follow-up as compared to women who are at low risk.

In summary, for normal-risk women, Pap smears should be performed approximately every 3 years. She should make sure that she has not used vaginal medications, tampons, or douched during the last 24 hours. Women at increased risk, including previous abnormal smears, multiple sexual partners, early onset of intercourse, HIV-infected women, women of low socioeconomic status, and smokers, are appropriate candidates for more frequent screening. In contrast to the USPSTF, the American Cancer Society recommends screening beginning at the age of 18 years every year with the consideration of less frequent screening in low-risk women after three normal yearly examinations. Older women who have not had adequate screening should be specifically targeted for screening.

SEE ALSO: Cervical cancer, Ovarian cancer, Uterine cancer

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Category: Cancer Screening