Screening: Pap and HPV Tests
Each year, approximately 12,000 women are diagnosed with cervical cancer in the United States. Yet cervical cancer is one of the most preventable cancers today. In most cases cervical cancer can be prevented through early detection and treatment of abnormal cell changes that occur in the cervix years before cervical cancer develops. We now know that these cell changes are caused by human papillomavirus, commonly known as HPV. The traditional test for early detection has been the Pap test. Now tests for HPV are available that can be used with the Pap test in women starting at 30 years of age and in women of any age when the Pap test alone has found slightly abnormal cell changes.
The Pap Test
The Pap test finds changes in the cells of the cervix (the mouth of the womb) that are not normal. When a female has a Pap test, she is positioned on an exam table and a device called a speculum is gently inserted to open the vagina. The speculum allows the healthcare provider to view the cervix and upper vagina. Once the provider can see the cervix, a "broom" device or a brush/spatula combination will be used to collect the cells. While the technique is a little different depending on the device chosen, in general, the provider will gently rotate the device in the endocervix (the cervical canal) and the ectocervix (the portion of the cervix extending into the vagina) to collect squamous and glandular cells. The cells are sent to a laboratory where they are prepared and evaluated under a microscope.
When a female gets Pap test, she is being screened for to make sure that there are no abnormal or precancerous changes in the cells on her cervix. If the Pap test results show these cell changes, this is usually called cervical dysplasia. Other common terms the healthcare provider may use include:
- Abnormal cell changes
- Precancerous cells changes
- CIN (cervical intraepithelial neoplasia)
- SIL (squamous intraepithelial lesions)
- "Warts" on the cervix
All of these terms mean similar things - it simply means that abnormalities were found. Most of the time, these cell changes are due to HPV. There are many types of HPV that can cause cervical dysplasia. Most of these types are considered "high-risk" types, which means that they have been linked with cervical cancer.
Just because a female has cervical dysplasia, it does not mean she will get cervical cancer. It means that her healthcare provider will want to closely monitor her cervix every so often - and possibly do treatment - to prevent further cell changes that could become cancerous over time if left unchecked.
The HPV Test
HPV tests can find any of the high-risk types of HPV that are most commonly found in cervical cancer. The presence of any of these HPV types in a woman for many years can lead to cell changes that may need to be treated so that cervical cancer does not occur. The HPV test is done at the same time as the Pap test by using a small soft brush to collect cervical cells that are sent to the laboratory, or the HPV testing sample may be taken directly from the Pap sample.
In women 30 and over, screening using both an HPV test and a Pap test is more likely to find abnormal cervical cell changes than either test alone. If both tests are negative (normal), a woman may safely have her next Pap and HPV test in three years depending on her past Pap test findings and other risk factors. For this reason, some women now may have an HPV test when they have their Pap test. It will still be important to continue having routine recommended preventative health exams.
After age 30, HPV is much less common. If you are over the age of 30 and you test positive for HPV you may have gotten it many years before and your immune system hasn’t gotten rid of it. Because HPV must be present for many years to cause cell changes, testing for HPV after the age of 30 is much more helpful.
In women under age 30, consensus guidelines do not currently recommend this. HPV is very common in women under the age of 30 and cervical cancer is very rare in this age group. Most women under 30 with HPV will get rid of the virus without treatment. So including an HPV test along with your Pap isn't helpful for younger women and might be harmful if it resulted in too many tests and unnecessary treatment.
Four tests are currently available for clinical use to check for “high-risk” types of HPV:
- The digene Hybrid Capture II ™ HPV test, produced by Qiagen
- The Hologic/Gen-Probe Corporation's Cervista™ HPV High-Risk (HR) test
- The Roche cobas® HPV test
- The APTIMA® HPV mRNA Assay, produced by Hologic/Gen-Probe
A word about genotyping: two “high risk” HPV types (also called “genotypes), HPV 16 and HPV 18, are responsible for about 70% of cervical cancers worldwide. Two tests on the market – the Roche cobas HPV test and Hologic’s Cervista HPV 16/18 Genotyping test - both check directly for HPV 16 and HPV 18. Gen-Probe’s APTIMA assay checks for three types, HPV 16 and HPV 18/45. Knowing if a woman has these types of HPV gives health care providers more insight into her risk for developing cervical cancer.
Preparing for a Pap or HPV Test
There are steps you can take to ensure you get the best possible results from your Pap or HPV test.
- Try to schedule the test on a day when you do not expect to be on your menstrual period. If your period begins unexpectedly and will be continuing on the day of your test, try to reschedule the appointment.
- Avoid sexual intercourse 48 hours before the test.
- Do not douche 48 hours before the test.
- Do not use tampons, or vaginal creams, foams, films, or jellies (such as spermicides or medications inserted into the vagina) for 48 hours before the test
There are many different systems that healthcare providers use to classify a Pap test. Within each system, there are different degrees of severity or abnormalities. The various classification systems and degrees of severity include:
Descriptive System: Mild dysplasia, Moderate dysplasia, Severe dysplasia
CIN System: CIN stands for cervical intraepithelial neoplasia. Results are classified as CIN 1, CIN 2, CIN 3
- ASC-US (Atypical Squamous Cells of Undetermined Significance): Means the results look borderline between “normal” and “abnormal” - often not HPV-related
- ASC-H (Atypical Squamous Cells-can not exclude HSIL):Borderline results, but may really include High-Grade lesions.
- Low-Grade SIL (LSIL) and High-Grade SIL (HSIL): SIL stands for squamous intraepithelial lesion. LSILs are considered mild abnormalities usually caused by an HPV infection. HSILs are considered more severe abnormalities and have a greater chance of progressing to invasive cancer.
Women with abnormal Pap test results are usually examined further for cervical problems. This may involve coming back for a colposcopy and biopsy, or coming back in a few months for another Pap test. If the Pap result is “ASC-US,” then a HPV-DNA test may be done in the lab to see whether HPV is causing this borderline “normal-abnormal” Pap result.