Each year in the US, 55 million women receive a Pap test to check for abnormal cells that might be an early sign of cervical cancer. Of these, 35 million tests show abnormalities that require medical follow-up, and about 12,000 women are diagnosed as having cervical cancer.

Recent development: Since 2006, when the pharmaceutical company Merck began TV and print advertisements for Gardasil, a vaccine against the mainly sexually transmitted human papillomavirus (HPV), which is present in up to 99% of cervical cancer cases, many women have been increasingly confused about their real risks for the disease and what role a vaccine may play in preventing it.

Gardasil is also FDA-approved for preventing certain vulvar and vaginal cancers in females and for preventing genital warts in males and females. It was recently approved to prevent anal cancer in males and females. Cervarix, another HPV vaccine, was approved by the FDA in 2009.

Sin Hang Lee, MD, is a renowned HPV expert, a pathologist who has studied cervical cancer for more than 50 years and trained in the laboratory of Dr. Georgios Papanicolaou, the scientist who developed the Pap test to detect cervical cancer. Dr. Lee's most important insights…

Fact 1: There is no cervical cancer crisis. Thanks to regular use of the Pap test, the incidence of cervical cancer has been dramatically reduced. Of the Pap tests performed annually in the US, only about 0.02% result in a diagnosis of cervical cancer when a biopsy is performed.

If all women got annual Pap tests-and the tests were analyzed properly (not all HPV tests distinguish between benign HPV strains, or genotypes, and those that may cause cancer) death from cervical cancer would be extremely rare. The disease is highly preventable if lesions are detected in a precancerous stage.

Note: The American College of Obstetricians and Gynecologists (ACOG) revised its recommendations for Pap tests in 2009. For women ages 21 to 30 without symptoms or risk factors, the ACOG recommends the test every two years and every three years for women age 30 and older who have had three consecutive normal tests. Discuss the frequency of your Pap tests with your doctor.

Fact 2: The concern over HPV infection is overblown. While HPV can cause cervical cancer, the story is more nuanced than people are led to believe from public service announcements and vaccine ads.

There are about 200 known genotypes of HPV, but only 13 are considered "high risk" for causing cervical cancer-HPV-16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 68. Of these, HPV16 and HPV-18 are believed to cause 70% of all cervical cancers. That means that you can have any of the 187 other genotypes without having an increased risk of developing cervical cancer. The prevalence of high-risk genotypes varies worldwide and depends in part on a woman's level of sexual activity.

Important: Nearly all cases of genital warts are caused by two low-risk genotypes, HPV-6 and HPV-11. This means that warts you can see and feel are annoying but usually not dangerous.

Even better news: Even though there is no treatment for HPV infection, women's immune systems are typically effective at fighting HPV. More than 90% of HPV infections disappear on their own and do not progress to precancerous stages or cancer. In fact, the average HPV infection lasts only about six months. This means that a woman who receives testing when the infection is active may be HPV-negative within a matter of months.

The women who should be most concerned about cervical cancer are those infected with a high-risk genotype in which the infection is persistent (lasting more than six months). Women typically undergo repeat testing every six months until the infection clears, and a biopsy may be recommended if an infection of the same genotype persists while the Pap test is still abnormal or questionable.

Fact 3: HPV vaccines don't guarantee cancer prevention. Gardasil prevents infection with four genotypes-the high-risk HPV-16 and HPV-18 and the low-risk-for-cancer, genital wart-causing HPV-6 and HPV-11. (Cervarix prevents only HPV-16 and HPV-18.)

Some women consider it useful to be protected against two of the 13 cancer-causing genotypes. However, most women are unaware that there is no evidence showing how long the vaccine will remain effective.

Important: I recommend that women who want to get the HPV vaccine ask their gynecologists to make sure that they are not already infected with HPV-16 or HPV-18.

There is some evidence that women who get the vaccine when they are infected with HPV—especially HPV-16 and HPV-18—have an increased risk of developing cervical cancer.

Reported side effects of the Gardasil and Cervarix vaccines include temporary pain and swelling at the injection site and headache. As of September 2010, the CDC reported 30 confirmed deaths of females who received Gardasil, though it is not proven that the vaccine caused these deaths. The agency did not publish data on reported deaths from Cervarix.

Fact 4: Not all HPV testing is adequate. Historically, HPV tests have not distinguished between benign and specific cancer-causing genotypes. Newer HPV tests, including Cervista HPV HR, are designed to detect when any of the 13 cancer-causing genotypes or the intermediate-risk genotype HPV-66 is present, but they do not identify the specific genotype. To identify the specific HPV genotype-with virtually no risk for false-positive results or misidentification-physicians can request a DNA sequencing test. This test is available from the nonprofit organization SaneVax, Inc., www.sanevax.org, for $50.

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