Cervical cancer screening

Patient information: Cervical cancer screening
Author
Brenda E Sirovich, MD, MS
Section Editors
Suzanne W Fletcher, MD
Barbara Goff, MD
Deputy Editor
H Nancy Sokol, MD
Disclosures

CERVICAL CANCER SCREENING OVERVIEW — The Pap smear (Pap test) is a test used to screen women for cervical precancer or cancer. Testing for human papillomavirus (HPV) is another type of test for cervical cancer sometimes used in women over age 30 and is usually performed in conjunction with the Pap test.

Pap tests find cervical cancer and precancer in the early stages when it can be treated, and thus may reduce the number of deaths from cervical cancer. This article reviews tests used to screen for cervical cancer and a description of both normal and abnormal Pap test results.

The evaluation and treatment of abnormal Pap tests are discussed separately. (See “Patient information: Management of atypical squamous cells (ASC-US and ASC-H) and low grade cervical squamous intraepithelial lesions (LSIL)” and “Patient information: Management of high grade cervical squamous intraepithelial lesions (HSIL) and glandular abnormalities (AGC)” and “Patient information: Treatment of precancerous cells of the cervix”.)

CERVICAL CANCER RISK FACTORS — The most important risk factor for cervical cancer is infection with the human papillomavirus (HPV). There are over 100 different types of HPV, however, most types of HPV do not cause cancer. At least 80 percent of women are exposed to the HPV virus during their lifetime. Most of the time, the body’s immune system gets rid of the virus before it does harm.

Researchers have labeled the HPV types as being high or low risk for causing cervical cancer.

Low risk types — HPV types 6 and 11 can cause genital warts and are low-risk types because they rarely cause cervical cancer. (See “Patient information: Genital warts in women”.)
High risk types — HPV types 16 and 18 are considered high-risk types because they may cause cervical cancer in some women.
HPV is spread by direct skin-to-skin contact, including sexual intercourse, oral sex, anal sex, or any other contact involving the genital area (eg, hand to genital contact). It is not possible to become infected with HPV by touching an object, such as a toilet seat. In 2006, a vaccine became available in the United States to help prevent infection with certain types of HPV. (See “Patient information: Human papillomavirus (HPV) vaccine”.)

Most people who are infected with HPV have no signs or symptoms. Most HPV infections are temporary and resolve within two years. When the virus persists (in 10 to 20 percent of cases), there is a chance of developing cervical precancer or cancer. However, it usually takes many years for HPV infection to cause cervical cancer.

CERVICAL CANCER SCREENING TESTS — There are several ways to screen for cervical cancer. The traditional screening test is called a Pap test.

Pap smear — The Pap test is a method of examining cells from the cervix (picture 1). The cervix is located at the lower end of the uterus (figure 1).

To perform a Pap test, a doctor or nurse will perform a pelvic exam and use a small brush or spatula to collect cells from the cervix. The cells are smeared on a glass slide (called a traditional Pap smear) or added to a preservative fluid (called liquid-based, thin layer testing).

HPV testing — An HPV test can be done along with a Pap test or as a separate test. Like a Pap test, the HPV test is done during a pelvic exam, using a small brush to collect a sample from the cervix.

If you are 30 years or older, your doctor or nurse may recommend HPV testing in addition to a Pap test. If your HPV test and Pap test are negative, repeat testing is not usually needed for three years. HPV testing may also be done if the results of your Pap test results are unclear.

Women who are under age 30 are not usually tested for HPV because many women in this age group have temporary infections, which will go away without treatment.

WHO SHOULD HAVE A PAP SMEAR?

Younger women — In the United States, the first Pap test is recommended at age 21; some other countries suggest that screening begin at age 25. Cervical cancer is very rare in younger women.

In the past, experts recommended that every woman have a Pap test every year. This has changed, and Pap testing is suggested every one to two years for most women age 21 to 29 and every two to three years for most women age 30 or older. In women who are 30 or older, the time between Pap tests may vary depending on the results of human papillomavirus testing. A woman’s other risk factors for cervical cancer may also affect these recommendations.

Even if you have had a vaccine for human papillomavirus, you will still need cervical cancer screening. (See “Patient information: Human papillomavirus (HPV) vaccine”.)

Older women — Most experts feel that women who are 65 years or older can stop having Pap tests if:

You have had Pap tests on a regular basis in the past
You have had at least three normal Pap tests in a row and no abnormal Pap tests in the past 10 years
After hysterectomy — Women who have had a total hysterectomy (your uterus and cervix were removed) do not need a Pap test, unless:

The hysterectomy did not remove your cervix (eg, if the hysterectomy was “subtotal”)
Your hysterectomy was done because of cervical cancer or precancer
You were exposed to diethylstilbestrol (DES) during your mother’s pregnancy
PREPARING FOR YOUR PAP SMEAR — For two days before your Pap test, do not put anything in your vagina (eg, spermicide, creams). A Pap test can be done at any time during your menstrual cycle.

PAP SMEAR RESULTS — The results from your Pap test will be available a few weeks after your visit. Pap test results may be reported as:

Negative — Pap tests that have no abnormal, precancerous, or cancerous cells are labeled as “Negative for intraepithelial lesion or malignancy.”

Abnormal results — Cervical cells may appear abnormal for a variety of reasons. For example, you may have a cervical infection, or you may have a precancerous area or even cervical cancer.

Follow up testing — If your Pap test is abnormal, or if your Pap test is normal but your HPV test is abnormal (positive), you may need follow up testing; the best strategy depends on several individual factors.

Follow up for abnormal Pap tests is discussed separately.

(See “Patient information: Management of atypical squamous cells (ASC-US and ASC-H) and low grade cervical squamous intraepithelial lesions (LSIL)”.)
(See “Patient information: Management of high grade cervical squamous intraepithelial lesions (HSIL) and glandular abnormalities (AGC)”.)
(See “Patient information: Treatment of precancerous cells of the cervix”.)
(See “Patient information: Colposcopy”.)
WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

 

Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient Level Information:

Patient information: Management of atypical squamous cells (ASC-US and ASC-H) and low grade cervical squamous intraepithelial lesions (LSIL)
Patient information: Management of high grade cervical squamous intraepithelial lesions (HSIL) and glandular abnormalities (AGC)
Patient information: Treatment of precancerous cells of the cervix
Patient information: Genital warts in women
Patient information: Human papillomavirus (HPV) vaccine
Patient information: Colposcopy

Professional Level Information:

Cervical cancer screening tests: Techniques and test characteristics of cervical cytology and human papillomavirus testing
Cervical cytology: Evaluation of atypical and malignant glandular cells
Cervical cytology: Evaluation of high grade squamous intraepithelial lesions
Cervical cytology: Evaluation of low grade squamous intraepithelial lesions
Overview of preventive medicine in adults
Screening for cervical cancer
Screening for cervical cancer in HIV infected women

The following organizations also provide reliable health information.

National Library of Medicine
(www.nlm.nih.gov/medlineplus/healthtopics.html)

American Society for Colposcopy and Cervical Pathology
(www.asccp.org)

American Cancer Society
(www.cancer.org, search for HPV)

National HPV and Cervical Cancer Public Education Campaign
Telephone: 1-866-280-6605
(www.cervicalcancercampaign.org)

Center for Disease Control and Prevention
(www.cdc.gov/)

American Social Health Association
(file://www.ashastd.org/)

REFERENCES
Koutsky LA, Ault KA, Wheeler CM, et al. A controlled trial of a human papillomavirus type 16 vaccine. N Engl J Med 2002; 347:1645.
Villa LL, Costa RL, Petta CA, et al. Prophylactic quadrivalent human papillomavirus (types 6, 11, 16, and 18) L1 virus-like particle vaccine in young women: a randomised double-blind placebo-controlled multicentre phase II efficacy trial. Lancet Oncol 2005; 6:271.
International Collaboration of Epidemiological Studies of Cervical Cancer, Appleby P, Beral V, et al. Carcinoma of the cervix and tobacco smoking: collaborative reanalysis of individual data on 13,541 women with carcinoma of the cervix and 23,017 women without carcinoma of the cervix from 23 epidemiological studies. Int J Cancer 2006; 118:1481.
Wright TC Jr, Cox JT, Massad LS, et al. 2001 Consensus Guidelines for the management of women with cervical cytological abnormalities. JAMA 2002; 287:2120.
American College of Obstetricians and Gynecologists. ACOG Practice Bulletin number 66, September 2005. Management of abnormal cervical cytology and histology. Obstet Gynecol 2005; 106:645.