ABNORNAL SMEAR TESTS

by D E Tucker MRCOG

Smear tests are offered to a large percentage of women in the UK at 3-yearly intervals. Being told that your smear test is not normal may cause distress and fear, however in the majority of cases it will just mean either repeating your test a bit sooner than normal or further investigation at the hospital.

Having an abnormal smear does not mean that you have cancer, or are going to develop it in the future.

Now that the National Screening Programme is well established, cervical cancer is extremely rare in women who attend regularly for smears.

Why do we have smear tests?

On a global basis, cervical cancer is the second most common cancer after breast cancer, accounting for about 15% of all cancers in women. It is known that before cancer of the cervix develops, there are 'early warning' changes in the cervix which are detectable by taking a smear. Once detected, the progression to cancer can be halted with the appropriate treatment. Screening and treating before cancer develops has led to a fall in the number of cases of cervical cancer by almost one half. Smears are offered to all women aged 20-65 years, and women over 65 who have not had preceeding normal smears.

The smear test samples the cells on the area of the cervix where cancer begins and a pathologist looks at these cells under a microscope, seeking out unusual-looking ones. From this the pathologist gives a result to your GP stating the degree of abnormality, if there is any.

What is seen in a normal smear?

A normal smear will have a sample of the cells from the area of the cervix known as the TRANSFORMATION ZONE. This is where the soft lining of the inner cervix meets the toughened lining of the outer cervix which sits in the vagina. The transformation zone is where changes which might lead to cancer first occur. After the doctor or nurse has taken the smear, they will wipe the brush or spatula onto a glass slide, ready for reading by the pathologist.

What is meant by an 'unsatisfactory' smear?

This result means that the pathologist could not satisfy himself that he has a good sample from the cervix. This might be because of too much blood or mucous being present, contamination by foreign material or inflammatory cells indicating a reaction by the body to infection or trauma. The pathologist might feel that there was not enough of the transformation zone sampled to be able to reassure you fully. In any case, it is unlikely to mean a cancerous or precancer finding. If you have several unsatisfactory smears, the pathologist may suggest referral to the hospital to see why this is happening.

How common is it to have an abnormal smear result?

Currently in the UK, 1-2% of women aged 25-35 years will have an abnormal smear. It is most common within this age group, being extremely rare before the age of 15 years and falling off to 0.5-1% after 40 years.

Does having an abnormal smear mean that I may get cervical cancer?

The degree of abnormality reported by the pathologist is important in answering this question and deciding the cancer potential of a smear. The smear is graded as being mildly, moderately or severely abnormal. A single 'mildly abnormal' smear is unlikely to represent significant short-term risk and the underlying changes may well regress to normal.

Defining percentages of smears which, left untreated, will progress to cancer is difficult since when looking at populations we do treat abnormal smears, and even the sampling process, to see what is present, may alter the progress. About 30-60% of untreated moderate or severely abnormal smears will progress to cancer over a period of about 10 years. Over the subsequent 10 years it is estimated that one-third of these cancers might become invasive with the potential for serious harm or death, if not treated.

Since the abnormal cells have been picked up on the smear test, further investigation and treatment will stop this progression. This is why the majority of cervical cancers occur in women who have not participated in the National Screening Programme.

What about a mildly abnormal smear?

Changes on the cervix associated with a mildly abnormal smear often regress, and the smear becomes normal again. Rather than refer you to the hospital straight away, it is common to repeat the smear in a few months time. If the mildly abnormal cells persist, further investigation is warranted to ensure that something more sinister is not being missed.

What is the significance of 'wart virus' on the smear?

About 2% of women will have evidence of wart virus infection on their smear even if they do not have obvious genital warts. Some variants of the wart virus are known to cause precancer. Overall, only about 15% of women with wart virus on their smear are at risk of developing precancer. Like the other mild changes, it is possible that the wart virus changes may resolve without any further action. Most doctors would suggest further investigation at the hospital if it persists on two smears.

What is involved in 'further investigation' of abnormal smears?

When you are referred to the hospital you will be seen by a gynaecologist, pathologist or genitourinary medicine physician who is specially trained in diagnosing and treating abnormalities of the cervix. The technique used is known as COLPOSCOPY.

The staff in the colposcopy unit realise that you will be quite anxious and will try to put you at ease. Colposcopy involves no more than the doctor passing a speculum (like when you have the smear taken), and then using a modified microscope (colposcope) to look at the cervix. The colposcope does not come into contact with you and the doctor looks into it at the end of the couch. This magnification makes it easier to see all of the transformation zone of the cervix and look for any abnormal areas that might be causing the unusual cells on the smear. If an area looks abnormal, a tiny biopsy (sample) is taken - this is not particularly painful as the biopsy is so small. This allows the pathologist who looked at your smear to see exactly where the unusual cells were coming from. Knowing this the doctor doing the colposcopy can treat the abnormal area accordingly.

Most treatments need no anaesthetic or only local anaesthetic and are carried out in the colposcopy unit. Treatment usually only takes about 20-30 minutes at most, and results in few after-effects. You will be asked to abstain from sex for 10 days or so.

Very occasionally, when the upper end of the unusual area cannot be seen, a general anaesthetic may be needed for the treatment. Some units also have a 'see and treat' policy, where biopsy and treatment occur together in one visit.