A New Look at the Pap Smear

Posted by Ronald | September 18, 2012  |  No Comment

Have you been instructed by your provider that you can have a pap smear every three years? Does that span of time lead to a sigh of relief or to anxiety? The recommendations for the frequency of pap smear screening have led to some confusion for many women, and it is important to understand the purpose of this test.

The pap smear is a cervical cancer screening test that was named after Dr. Georgios Papanikolaou who documented the cellular changes leading to this malignancy in 1928. It had been used exclusively for many years to detect premalignant and malignant cells of the cervix. The cervix is the lower part of the uterus that can be seen protruding into the upper part of the vagina when a speculum is inserted. It is also the area that dilates during labor for the delivery of infants. Because premalignant changes of the cervix rarely have any symptoms, women world-wide had historically been diagnosed at later stages of cervical cancer. The rate of cervical cancer has dropped significantly in the U.S. since implementing this mode of screening.

For decades, women had been encouraged to report to their doctors for an “annual exam” that included this test. The recommendations changed in recent years. Women who were not considered to be in high risk groups were encouraged to get their pap smear every other year between the ages of 21-29. Women who are at low risk should have a screen every three years when they are 30 or older if they have had three consecutive normal ones. Additionally, teens were instructed that they no longer needed pap smears and initial screening should begin at the age of 21. This, however, did not negate the need for adolescents who are sexually active to have routine evaluations for sexually transmitted infections and contraceptive needs.

One of the most significant findings since the development of the pap smear was the association of human papillomavirus (HPV) infections with anogenital cancer and most commonly cervical cancer. There are over 100 strains of HPV, of which approximately 40 can be transmitted sexually. Exposure occurs from anogenital skin to skin contact that does not require penetration and includes oral sex. It is estimated that 50-80 percent of all sexually active people will have HPV at some point in their lifetime. Those strains that potentially lead to cervical cancer or other anogenital cancers are designated as high risk HPV.

The most prevalent strains with cervical cancer are type 16, 18, 31 and 45. There are low risk strains as well that can cause oral and anogenital warts. These strains do not have an association with cancer. Because high risk HPV is believed to be the culprit in cervical cancers, it has become relevant to detect women who could be at risk. Testing for high risk HPV is now recommended for all women who are 30 and older. Human papillomavirus can be detected in the solution used while collecting the routine pap smear. Harboring the virus in this age group increases the potential for malignant change. If a high risk strain of HPV is not detected during screening, some thought leaders are considering extending screening intervals to five years for low risk women over 30.

Adolescents are believed to have the highest exposure to HPV partly because of their sexual practices and the degree of cellular maturation of the cervix. Studies have shown, however, that they will usually clear the virus through the action of a robust immune system. Because cervical cancer is extremely rare in teens and young adults, screening isn’t initiated until 21 to decrease unnecessary treatments for a process that is likely to resolve spontaneously. Historically, aggressive treatment in this group has led to preterm labor and delivery as a result of the significant reduction in the length of the cervix. A woman can transfer an HPV infection to her child during pregnancy but this occurs very rarely. Exposed children can also develop a condition called juvenile onset recurrent respiratory papillomatosis. This disorder is on the rise but remains rare at present.

There are no current medications to cure human papillomavirus, but the immune system can be very effective in clearing the infection. Current thought stipulates this can occur within 24 months. Exposure can be decreased through routine latex (or polyurethane) condom use, but this does not reduce the risk of external surface exposure (genital skin, scrotal skin, etc.) A weakened immune system, such as in people who are HIV positive or require chronic use of steroids, is less likely to clear the virus rapidly. The effect of cigarette smoking on the immune system has also been associated with increased risk of cervical cancer.

Vaccines have been developed to prevent infection with certain strains of HPV. The Gardasil vaccine was developed to protect against 4 strains: 6 and 11 (low risk strains) which cause genital warts and 16 and 18 (high risk strains). These two high risk strains are associated with 70 percent of all squamous cervical cancers. This vaccine requires a series of three injections over a six-month period. It is approved by the U. S. Food and Drug Administration for females and males between the ages of 9-26 and is most effective when given prior to first sexual contact. Physicians in this country recommend that it be administered at 11-12 years of age because of a stronger immune response. Vaccination recommendations in males are slightly different; adult males from 22-26 should speak with their providers about available options. The Cervarix vaccine protects against types 16 and 18 only and is only approved for female risk reduction.

With what we now know, cervical cancer is preventable in the United States where access to care is available. The National Breast and Cervical Cancer Early Detection Program assures that even underserved women in all 50 states, Washington, DC, five U.S. territories and 12 tribes have access to screening. With routine checkups, a premalignant finding can be cured 90-95 percent of the time. I encourage all women to discuss the current screening recommendations with their healthcare provider and develop a regimen that is appropriate for you.

Dr. Stephanie Sweet is a board certified Obstetrician/Gynecologist who believes patient education is an essential component to effective healthcare. She has focused her efforts in recent years on community outreach for the prevention of sexual transmission of disease and HIV through the development of outreach programs such as SEXPOSURE and Spread the Word. Dr. Sweet has worked in an academic setting for the majority of her career and is currently practicing at UC Davis Medical Center in northern California.

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