Patient InformationPrevention of Cancer of the Cervix
- The Normal Cervix and Dysplasia
- The Human Papilloma Virus - HPV
- Vaccination and Screening to Prevent Cancer
- High Grade Dysplasia
a) The Normal Cervix and Dysplasia
The Cervix is the “neck of the womb” (uterus). It is the canal joining the cavity of the uterus to the vagina.
The canal of the cervix is lined with mucus glands. At the end of the canal the mucus glands change to form the smooth skin on the outside of the cervix. This transformation process is called metaplasia and it occurs throughout a lifetime. The area where this metaplasia occurs is called the transformation zone. This is the area where most cancers of the cervix will start.
When the cells undergoing metaplasia have an altered size, this is a pre-cancer warning sign called dysplasia. The skin with dysplasia remains normal. Dysplasia is not cancer. Dysplasia can resolve spontaneously. When dysplasia persists for some years there is an increased chance that the skin will change into cancer. Dysplasia is usually associated with the presence of a Human Papilloma Virus.
b) The Human Papilloma Virus - HPV
The human papilloma virus is a very common virus that is present in the skin. HPV does not enter the human body any deeper than the skin. Most people will have a HPV from time to time and not know it. Since the introduction of the new Cervical Screening Test many women of all ages up to the age of 70 have discovered the presence of HPV. Most of these women had regular smears previously that were always reported to be negative. These results show that many people have HPV types that can lead to cancer for many years without ever having dysplasia or cancer. The “high risk” HPV types do not always cause dysplasia or cancer. When the HPV is found on a Cervical Screening Test the report often states that there is a human papilloma virus “infection”, however the skin is normal and will not be inflamed as one might expect when there is an infection with something like bacteria for instance. There is usually no sign of inflammation or infection in the skin. Only 1% or 2% of people with papilloma virus will get some skin changes which are usually warts. There are over 200 types of HPV but only 15 of these may lead to cancer. Two types out of these 15, “Type 16” & “Type 18”, lead to 80% of cervix cancers. The types that cause warts do not cause cancer. Most of the time the HPV moves on without causing any harm.
c) Vaccination and Screening to Prevent Cancer
Cervix cancer arises after years of persisting high-risk HPV associated dysplasia. Therefore vaccination against the HPV will prevent its persisting in the skin and therefore be a very effective method of prevention of cervix cancer. All teenagers should have vaccination against the Human Papilloma virus types that may lead to cancer. Older women (at any age) should consider the vaccination when their situation deems that a vaccination would be appropriate. (Discuss this with your GP or Specialist).
The Cervical Screening Test - CST
This is a test to detect the Human Papilloma Virus and Dysplasia on the normal cervix. The Cervical Screening Test has replaced the Pap Smear as primary screening because it is more accurate and more effective at prevention of cancer of the cervix. “Screening” means doing a simple test on “normal” skin, when there are no symptoms, to detect the signs that precede the development of cancer. This skin can be treated whilst it is normal thus preventing it from changing to cancer. The Screening Test is a DNA test to detect the HPV types that may lead to cancer. When there are no such HPV types detected the recommendation is to repeat the Screening Test at five yearly intervals. This will be more effective than the previous two yearly smears because of the accuracy of the DNA test compared to the smear test.
Reminder Note: Remember that screening means testing when things are normal. If symptoms occur tests should be carried out immediately rather than in five years.
The Positive CST
The CST is for everyone to have as a screening test to select people from the general population who require a closer examination of the skin on the cervix. This closer examination is called a Colposcopy. A positive CST does not mean that dysplasia is present. A biopsy of the skin is needed to diagnose dysplasia. A colposcopy examination can show which area of the skin needs to be biopsied. Pathologists examine the biopsied skin and come to a diagnosis.
When a “high risk” HPV is detected on the CST the sample is further examined for signs of dysplasia. The report will use terms referring to low or high grade “lesions” and a colposcopy will be recommended. The word “lesion” can be misleading to many people who think this may be cancer. It is unlikely that there are any “lesions” on the skin. The terminology refers to the presence of a microscopic sign in normal skin.
Remember: A CST is a “screening” test on normal skin. To diagnose the pre-cancer sign in normal skin a colposcopy and biopsy is required. (The skin remains normal.)
d) High Grade Dysplasia
When there is an area of skin on the cervix with proven high grade dysplasia it can be removed while it is normal. This will prevent any chance of that skin changing to cancer in the future. New skin heals in its place and the cervix remains normal. The decision as to if and when the skin needs to be removed depends on the person’s age, plans for pregnancies, and the individual characteristics found on the colposcopy examination. After the cervix heals from excision of the dysplasia there is a small chance that further dysplasia will be present in the new skin and some people may have that area of skin removed on more than one occasion. If the cervix skin is removed on multiple occasions the cervix may be weakened which may lead to cervical incompetence. This may result in an extremely premature birth of a baby in future pregnancies. Therefore, in young people, surgery may be postponed until after further observation, keeping the cervix skin under surveillance by repeating smears and colposcopy examinations. The HPV often leaves the skin and the dysplasia resolves spontaneously meaning surgery would then be avoided.