Why do I need a screening smear?
Cervical cancer is a preventable cancer. In contrast to other sites in the body, lesions which could develop into cancer can be detected at a very early stage. Where high-risk abnormalities are managed and treated at an early stage, it is still possible to prevent cancer developing. Today, we have sophisticated screening techniques, in particular the HPV test, via which patients can be guaranteed almost complete protection against this cancer. In vaccinated women, screening needs to be continued as they still run the risk of being exposed to strains of HPV other than those contained in the vaccine.
What is a smear?
The smear is a screening test in which cells are taken from the surface of the cervix. The cells are then examined under the microscope. Depending on the appearance of these cells, it is possible to identify whether the cervix is normal, whether it is affected by an infection or abnormalities which could be lesions called dysplasia (2% of women every year), or whether cervical cancer is present (every year, around one woman in 10,000 is affected by cervical cancer in France). The screening smear is a fairly good test for detecting abnormal cervical cells but it is not 100% reliable. Even where the test is carried out properly, there is a small risk that the result is found to be “normal” although cervical abnormalities exist. This is why it is very important to have a screening smear at regular intervals throughout your life (the frequency being advised by the gynaecologist) so that any abnormalities not picked up on the previous smear are not overlooked.
Which women need to be tested?
All women from 20 to 70 years of age need to be screened for cervical cancer because pre-cancerous lesions of the cervix are asymptomatic. It is imperative to understand that to be protected against cervical cancer, regular screening is essential. The screening test is offered to all women, or to all who have been sexually active. In young girls who become sexually active at a young age, the screening test can be performed before the age of 20 years. After the menopause, smears are still necessary whether or not you are taking hormone replacement therapy. Following a hysterectomy, the vaginal smear still needs to be continued at regular intervals.
What happens in a smear?
The sample of cells is taken using a spatula or brush selected to suit the size and appearance of the cervix. The process involves scraping the surface of the cervix, in particular the most sensitive zone where abnormalities develop, called the “transformation zone”, which is usually located between the opening of the cervix and the external part of the cervix. The cells thus taken are spread on a slide and fixed. The slide is then sent to the laboratory to be viewed under a microscope.
The screening smear: Who? When? How?
The smear is generally taken by a doctor, usually your gynaecologist, but sometimes your GP. The doctor uses a speculum to part the walls of the vagina and access, right at the back of the vagina, a convex zone called the cervix or “neck of the womb”. This test should not be carried out during a woman´s period or breakthrough bleeding, nor should vaginal douches or creams, pessaries or gels, or tampons be used for two days prior to the test. The woman should also abstain from sex for two days prior to the smear.
During your consultation, an examination will take place on the examination couch. The doctor will use a speculum to access your cervix. This examination is not painful and takes less than two minutes. You should try to relax so that you do not contract your vaginal muscles which would make the examination difficult.
How are smears categorised? The terminology used.
* The Papanicolaou terminology
By “inventing” the smear, Papanicolaou also created a cell classification which, in the past, was used by all laboratories but is used more rarely now.
- Class 1 corresponds to the absence of abnormal cells.
- Class 2 means that the examination shows atypical cells but without any sign of malignancy. Very frequent, like Class 1, it corresponds in fact to inflamed samples (the cervix currently has a slight, non-serious inflammation).
- Class 3 also means the presence of atypical cells but suggests that a “pre-malignancy” is involved.
- Class 4 suggests this presumption of malignancy more strongly.
- Class 5 means the presence of malignant cells.
* The terminology of WHO (World Health Organization)
Knowledge has moved on and the terminology of Papanicolaou is now somewhat inadequate.
The WHO wanted to update the classifications. According to its terminology, abnormalities are viewed in terms of dysplasia, i.e. changes in the appearance of the cells. The method of analysis also allows the scale of abnormalities in the cervical mucous membrane to be evaluated, by observing the squamous cells released from the entire thickness of the cervix. The cell analysis is therefore described thus:
- Absence of dysplasia
- Mild dysplasia: this means that the “abnormal” cells are found in the lower third of the mucous membrane of the cervix.
- Moderate dysplasia: the abnormalities occupy the lower two-thirds of the cervical mucous membrane.
- Severe dysplasia: the entire thickness of the cervical mucous membrane contains abnormal cells.
* The Bethesda terminology
This is the most recent terminology and that which is recommended. It was defined by the National Cancer Institute located in Bethesda, near Washington, and makes the following distinctions:
- Normal smear: no abnormal cells
- Unclear smear: simply, this means that the sample is “contaminated” by microbes, an infection, an inflammation, too much blood, or that it does not contain the necessary complete cell sample containing cells from different parts of the cervix.
- Borderline smear (also called ASCUS): this means that the cells are benign or dysplastic with no additional indications.
- LSIL (low-grade squamous intraepithelial lesion) or low-grade CIN (cervical intraepithelial neoplasia): mild dysplasia and / or presence of condyloma. The presence of HPV is identified by koilocytes (cells filled with virus), possibly with mild dysplasia i.e. an abnormality of the cells in the lower third of the epithelium (in which case this is detailed in the result).
- HSIL or high-grade CIN includes moderate or severe dysplasia: the lesions are more extensive but still benign. The cell abnormalities occupy two-thirds of, or the entire, epithelial lining. Signs of papillomavirus infection are also found.
- Abnormalities of the glandular cells: part of the sample must contain cells from the mucous membrane of the internal cervix, called glandular epithelium. A dysplasia located in this site is specifically mentioned in the smear result.
What happens after the smear?
Once a smear has been carried out and the results sent back by the laboratory, it is important that your doctor should comment on your results. At this time, make an appointment for your next smear.
If the smear is normal and there is no particular medical history, a two-year interval is generally sufficient.
If your smear shows minor changes (ASCUS) to the cells, your doctor may offer you the following options:
- to repeat the smear six months later to re-assess your cervix; if it is still not normal, he will recommend a colposcopy; if it is negative, he will repeat the smear six months later;
- to carry out an HPV test to clarify the smear results and define your risk profile; if it is positive, he will refer you for colposcopy; if it is negative, he will offer a check-up in one year´s time;
- to carry out a microscopic analysis of the cervix, called a colposcopy, and use this opportunity to take a sample, called a biopsy, from the abnormal zone of your cervix,.
If your smear shows clear or major abnormalities (low-grade or high-grade), colposcopy will always be suggested.
What happens if the smear is not satisfactory?
If no cells from the transformation zone (glandular cells or metaplastic cells) are found in the smear, this may indicate that the sample was not collected properly. On the other hand, if the smear shows a major inflammation or a lot of mucus which could falsify its interpretation, it may not have been possible to read it properly. In cases such as these, the smear is said to be unsatisfactory. The smear should then be repeated under better conditions.
What causes the changes to the cervical cells detected by the smear?
The papillomavirus (HPV) causes the majority of changes to the cells of the cervix. Papillomavirus infection is very commonly encountered in a lot of people. In general, the virus is transmitted during sex or by intimate contact. One of the areas most vulnerable to the virus is the transformation zone of the cervix.
All changes to the cells of the cervix are not necessarily abnormal. Abnormalities associated with the risk of development into cancer are the only ones where papillomavirus is found. If the HPV test is negative, there is practically no risk of developing marked cervical dysplasia - subject to this negative status persisting for a number of months. If the test is positive, the changes to the cells in the smear can be considered to be abnormal and then colposcopy and appropriate treatment can be planned. The presence of HPV is not a serious symptom but simply a sign of a process, which is usually benign, but which needs to be taken into account so that it can be properly managed. In any event, even if the HPV test is negative, screening still needs to be carried out at regular intervals.
In practical terms, what needs to be done depending on the results?
Whatever the terminology used, the result of a smear is simply an evaluation made on the basis of cells collected from the surface of the cervix which indicate the cellular composition of the mucous membrane. This examination does not always give an exact image of the actual presence of lesions. It is an alarm signal. It up to the gynaecologist to interpret it and, if appropriate, have it confirmed by additional examinations.
Normal or mildly-inflammatory smears mean that there is currently no risk. The next check-up will be carried out one to three years later.
If it is difficult to interpret or contains a large number of blood cells or microbes, or likewise if it does not contain a sample of all types of cells (the gynaecologist can figure out these details from all the smear results), the smear must be repeated in three to six months. By then, the parasites or microorganisms which prevented interpretation will have been eliminated. Any mycosis, for example, will have been treated or, in a post-menopausal woman, an oestrogen-based treatment will be offered to correct the presence of cells that were altered due to hormone deficiency. At the check-up smear, the physician must endeavour to collect a sufficient number of cells from the entire cervix so that the sample is as complete as possible.
Smears with atypical squamous cells of undetermined significance (ASCUS according to the Bethesda terminology) are smears where no pronouncement can be made about the exact situation. Reactional cell changes are usually involved, which do not correspond to any serious abnormality. More rarely, there is a dysplasia.
To decide what the situation is, a viral HPV test can be suggested. The absence of high-risk HPV almost certainly rules out the existence of a lesion, and means that the patient can be reassured. In this case, no other tests are necessary. On the other hand, the presence of high-risk HPV justifies carrying out a colposcopy (microscopic examination of the cervix allowing samples or biopsies to be taken from the zones concerned).
A colposcopy can be offered immediately, although this technique requires a certain level of experience to be effective.
Low-grade lesions or mild dysplasia regress spontaneously in approximately 50% of cases. It is sometimes sufficient to wait six months to confirm this diagnosis with a second smear. It is often preferable to offer colposcopy immediately as these abnormalities can be due to more serious lesions. If they have not disappeared, they are likely to develop into a high-risk lesion.
Colposcopy enables the cervix and its mucous membrane to be studied under the microscope and a sample (biopsy) to be taken, still under the microscope, of lesions located on the relevant sites. The analysis of the mucous membrane gives a precise reflection of the cellular composition.
High-grade lesions or moderate to severe dysplasia confirmed by biopsy, under colposcopy, will be treated in accordance with an appropriate protocol.
In any event, the gynaecologist will adapt his therapeutic strategy to prevent any development into cancer, with an efficacy approaching 100%.
How often is a screening smear needed?
There is no consensus about the frequency of smears.
In Scandinavian countries, where screening is systematic, there is a quality control for smears (they are read twice). Figures show that a 3-yearly frequency enables the incidence of cervical cancer to be reduced by 91%. An annual frequency results in a 93% reduction.
In France, gynaecologists are in favour of a frequency left to their discretion, depending on the individual woman´s risk factors. These factors include repeated genital infections (salpingitis, chlamydia), the presence of condyloma, early onset of sexual activity, number of partners, smoking etc.