Cervical screening makes it possible to find and treat cervical cancer in the early stages. The test involves scraping a small sample of cells from the surface of the woman’s cervix.
According to the National Cancer Institute, regular screening reduces the incidence and mortality of cervical cancer by 80 percent.
In the United States, in 11,955 women were diagnosed, and 4,217 women died from cervical cancer in 2013.
Deaths from cervical cancer in the U.S., however, are declining by around 2 percent each year due to progress in diagnosis and treatment.
The risk of cervical cancer can be severely reduced with regular screenings.
Cervical cancer affects the cervix, the narrow portion of the lower part of the uterus, where it joins the top end of the vagina. It has a conical or cylindrical shape, and it protrudes through the end of the vagina.
The main cause of cancer is human papillomavirus (HPV). HPV is found in around 99 percent of cervical cancers, although most cases of HPV do not become cancerous. Having HPV is the largest risk factor for cervical cancer.
Screening can show abnormal cells. If further testing proves that these are cancerous, treatment can be provided to prevent cancer from developing.
It normally takes 3 to 7 years for “high-grade,” or severe, abnormalities to become cervical cancer.
Cervical cancer screening can involve testing for human papillomavirus (HPV), the Pap, or smear test, and liquid-based cytology, an alternative to the Pap test. The doctor may also carry out a physical examination of the pelvis at the same time.
The Pap smear can be carried out with a swab.
Liquid-based cytology (LBC): A speculum is placed inside the vagina and the doctor scrapes the cervix with a small brush, which collects cervical cells. The doctor breaks off the head of the brush, places it in a small pot of liquid, and sends it to the lab.
The Pap smear: The health professional inserts a speculum into the patient’s vagina and spreads it open to allow access to the cervix. They then collect a sample of cells by scraping the outer opening of the cervix with a spatula. The cells are placed directly onto a microscope slide and sent to the lab. In the lab, cells are carefully examined. Any abnormal cells are reported.
Test results can take up to 3 weeks.
The Pap test takes its name from the Greek doctor, George Papanicolaou, who, with a Romanian doctor, Aurel Babeş, developed the test in the late 1920s.
Studies indicate that both types of test are valid and more labs are doing both LBC analysis along with the traditional Pap test analysis.
What the results mean
Cervical screening tests results can be normal, unclear, or abnormal.
Normal: there were no changes in the cells on the cervix.
Unclear: the cells look like they could be abnormal and the pathologist could not see if there were significant changes that could indicate precancer. These abnormal cells could relate to HPV, an infection, pregnancy, or life changes.
Abnormal: changes were found on the cervix. Abnormal cells do not always indicate that cancer is present. Further tests and treatment will be required to see if this is cancer or becoming cancerous.
In an unclear result, cell changes are present, but the cells are very near normal and will be likely to resolve on their own. The patient will probably be invited to repeat the test within 6 months.
Cervical erosion can lead to an unclear result. Sometimes referred to as an ectropion, cervical erosion means the glandular cells can be seen on the surface of the cervix.
Erosions are common, especially among women who are using the contraceptive pill, teenagers, and pregnant women. There may be some slight bleeding after sex. Most cases resolve without treatment.
An abnormal result means that the pathologist detected changes in the patient’s cervix. This does not necessarily mean that the woman has cervical cancer. In most cases, there is no cancer.
The abnormal changes in the cervical cells are often due to HPV. If changes are “low-grade”, they are minor. If they are “high-grade”, they are more serious. Most minor changes resolve without treatment.
More serious changes can eventually become cancerous if they are not removed. They are usually called “precancer.” It is vital that the patient does not let these changes get worse.
Further tests will be required to confirm this. Cervical cancer is easier to treat if it is diagnosed early.
Rarely, the test results might indicate the presence of cervical intraepithelial neoplasia (CIN).
This probably means that there are pre-cancerous cells. It does not mean the patient has cervical cancer.
It means there are slightly abnormal cells that could develop into cancer eventually if left untreated.
The results may show the following:
- CIN 1 (mild cell changes): one-third of the thickness of the skin that covers the cervix has abnormal cells
- CIN 2 (moderate cell changes): two-thirds of the thickness of the skin that covers the cervix has abnormal cells
- CIN 3 (severe cell changes): all the thickness of the skin that covers the cervix has abnormal cells
A biopsy of the cervix will need to confirm these results.
Sometimes the results reflect a problem with the test rather than the presence of any abnormal cells.
The patient may have to repeat the test because the sample was “inadequate,” meaning that it could not be read properly.
An inadequate sample could be due to:
- Too few cells being taken
- The patient having an infection so that the cells could not be seen clearly enough
- Menstruation, if the presence of blood makes it hard to see the cells properly
- Inflammation of the cervix, making it hard to see the cells clearly enough
In any of these cases, the woman will be asked to undergo another test.
According to the Center for Disease Control and Prevention (CDC), more than 3 million women get abnormal or unclear PAP test results, of which only about 10,000 have cervical cancer.
If she has an infection, the infection will need to be treated first.
Screening: Who and how often?
The American Cancer Society makes recommendations for regular screening at different ages.
From 21 to 29 years, they recommend that women should have a Pap smear every 3 years.
The guidelines recommend that HPV testing should not be used to screen for cancer in this age group. The HPV DNA test identifies a number of infections that are not linked to cancer, and a positive HPV test often does not mean that that woman will develop cancer.
The presence of the HPV virus can be a strong indicator of cervical cancer.
In one study, 86.7 percent of women who tested positive for HPV did not develop cancer in at least the following 10 years.
From 30 to 65 years, they recommend a Pap test combined with an HPV test every 5 years. Alternatively, they suggest Pap testing alone every 3 years. The National Cancer Institute, however, warns that a combined HPV and Pap test can lead to more false positives, more testing and more invasive procedures.
After the age of 65 years, women who have had regular screening with clear results in the last 10 years can stop screening. However, if a woman’s test has shown a serious pre-cancer within the last 20 years, such as a CIN2 or a CIN3, she should continue screening until 20 years after the date when the cancer was found.
A woman with a high risk of cervical cancer can undergo screening more often. Those at higher risk include women with a suppressed immune system, for example, because of HIV, organ transplant, or long-term steroid use.
After a total hysterectomy, in which the cervix was removed, screening is no longer necessary. However, if the hysterectomy did not remove the cervix, or if it was performed because of cancer, screening should continue.
Women who have been vaccinated against HPV should still have these screenings.
A woman who has, or has had, cervical cancer or pre-cancer, and those with HIV infection will have their own screening and treatment plan.
Cervical screening is no longer required yearly. Additional screening can cause more harm than benefit. A false positive result can not only cause stress, but it can lead to unnecessary procedures that may have long-term risks.
Younger women are more susceptible to low-grade squamous intraepithelial lesions (LSIL) that often resolve without treatment.
There is concern that treating these lesions may lead to fertility problems and pregnancy complications, including preterm delivery and preterm rupture of membranes.
Is it worth screening?
As technology advances and tests become more effective, guidelines change. In 2017 to 2018, medical associations will be reviewing the guidelines, and this may affect the use of the HPV test and the frequency of screening.
A cervical cancer diagnosis can be avoided when it is caught early enough.
The Centers for Disease Control and Prevention (CDC) note that the Pap test is “one of the most reliable and effective screening tests available.”
However, it only tests for cervical cancer. A woman who has unusual symptoms should see her doctor, as this could be a sign of vaginal, ovarian, vulvar, or uterine cancer.
Screening tests can be expensive, but recommended screening is normally covered by health insurance.
People on a low income, or who do not have health insurance, may qualify for a free or low-cost Pap test through the National Breast and Cervical Cancer Early Detection Program.