Cervical Cancer Screening (PDQ®)
What is screening?
Screening is looking for cancer before a person has any symptoms. This can help find cancer at an early stage. When abnormal tissue or cancer is found early, it may be easier to treat. By the time symptoms appear, cancer may have begun to spread.
Scientists are trying to better understand which people are more likely to get certain types of cancer. They also study the things we do and the things around us to see if they cause cancer. This information helps doctors recommend who should be screened for cancer, which screening tests should be used, and how often the tests should be done.
It is important to remember that your doctor does not necessarily think you have cancer if he or she suggests a screening test. Screening tests are given when you have no cancer symptoms.
If a screening test result is abnormal, you may need to have more tests done to find out if you have cancer. These are called diagnostic tests.
General Information About Cervical CancerAnatomy of the female reproductive system. The organs in the female reproductive system include the uterus, ovaries, fallopian tubes, cervix, and vagina. The uterus has a muscular outer layer called the myometrium and an inner lining called the endometrium.
Cervical cancer usually develops slowly over time. Before cancer appears in the cervix, the cells of the cervix go through changes known as dysplasia, in which cells that are not normal begin to appear in the cervical tissue. Later, cancer cells start to grow and spread more deeply into the cervix and to surrounding areas.
See the following PDQ summaries for more information about cervical cancer:
Cervical dysplasia occurs more often in women who are in their 20s and 30s. Death from cervical cancer is rare in women younger than 30 years and in women of any age who have regular screenings with the Pap test. The Pap test is used to detect cancer and changes that may lead to cancer. The chance of death from cervical cancer increases with age. Deaths from cervical cancer occur more often in black women than in white women.
Although most women with cervical cancer have the human papillomavirus (HPV) infection, not all women with an HPV infection will develop cervical cancer. Many different types of HPV can affect the cervix and only some of them cause abnormal cells that may become cancer. Some HPV infections go away without treatment.
HPV infections are spread mainly through sexual contact. Women who become sexually active at a young age and have many sexual partners are at increased risk for HPV infections.
Other risk factors for cervical cancer include:
- Giving birth to many children.
- Having many sexual partners.
- Having first sexual intercourse at a young age.
- Smoking cigarettes.
- Using oral contraceptives ("the Pill").
- Having a weakened immune system.
Cervical Cancer Screening
Some screening tests are used because they have been shown to be helpful both in finding cancers early and in decreasing the chance of dying from these cancers. Other tests are used because they have been shown to find cancer in some people; however, it has not been proven in clinical trials that use of these tests will decrease the risk of dying from cancer.
Scientists study screening tests to find those with the fewest risks and most benefits. Cancer screening trials also are meant to show whether early detection (finding cancer before it causes symptoms) decreases a person's chance of dying from the disease. For some types of cancer, the chance of recovery is better if the disease is found and treated at an early stage.
Clinical trials that study cancer screening methods are taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI Web site.
Regular screening of women between the ages of 25 and 60 years with the Pap test decreases their chance of dying from cervical cancer. In women younger than 25 years, screening with the Pap test may show changes in the cells of the cervix that are not cancer but lead to further testing and possibly treatment. Screening with the Pap test is not helpful in women older than 60 years who have had recent negative Pap tests.
A Pap test is a procedure to collect cells from the surface of the cervix and vagina. A piece of cotton, a brush, or a small wooden stick is used to gently scrape cells from the cervix and vagina. The cells are viewed under a microscope to find out if they are abnormal. This procedure is also called a Pap smear. A new method of collecting and viewing cells has been developed, in which the cells are placed into a liquid before being placed on a slide. It is not known if the new method will work better than the standard method to reduce the number of deaths from cervical cancer.Pap smear. A speculum is inserted into the vagina to widen it. Then, a brush is inserted into the vagina to collect cells from the cervix. The cells are checked under a microscope for signs of disease.
After certain positive Pap test results, an HPV DNA test may be done to find out if the HPV infection that is causing the abnormal cells is one that is linked to cervical cancer. In women aged 30 or older, the HPV DNA test and the Pap test are used to screen for HPV infection. In women younger than 30 years, HPV infections are common but usually do not last long or cause problems.
Screening clinical trials are taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI Web site.
Risks of Cervical Cancer Screening
Decisions about screening tests can be difficult. Not all screening tests are helpful and most have risks. Before having any screening test, you may want to discuss the test with your doctor. It is important to know the risks of the test and whether it has been proven to reduce the risk of dying from cancer.
Screening test results may appear to be normal even though cervical cancer is present. A woman who receives a false-negative test result (one that shows there is no cancer when there really is) may delay seeking medical care even if she has symptoms.
Screening test results may appear to be abnormal even though no cancer is present. Also, some abnormal cells in the cervix never become cancer. A false-positive test result (one that shows there is cancer when there really isn't) can cause anxiety and is usually followed by more tests and procedures (such as colposcopy, cryotherapy, or LEEP), which also have risks. The long-term effects of these procedures on fertility and pregnancy are not known.
Women aged 20 to 24 are most likely to have abnormal Pap test results that lead to further testing and treatment.
Studies show that the number of cases of cervical cancer and deaths from cervical cancer are greatly reduced by screening with Pap tests. Many doctors recommend a Pap test be done every year. New studies have shown that after a woman has a Pap test and the results show no sign of abnormal cells, the Pap test can be repeated every 2 to 3 years.
The Pap test is not a helpful screening test for cervical cancer in the following groups of women:
- Women who are younger than 25 years.
- Women who have had a total hysterectomy (surgery to remove the uterus and cervix) for a condition that is not cancer.
- Women who are aged 60 years or older and have a Pap test result that shows no abnormal cells. These women are very unlikely to have abnormal Pap test results in the future.
The decision about how often to have a Pap test is best made by you and your doctor.