One in 33 cervical smears is abnormal. One in 4,000 women develop cervical cancer each year. The vast majority of women with abnormal smears will never get cancer. But many of them think they will. So how can we stop all this worrying?

The short answer would be to stop cervical screening (after all, it has never been proven to work) but it's almost impossible to take away something that's been forced on us for 30 years. So researchers in Bristol and Cardiff set about reducing the unnecessary psychological damage of the mildly abnormal smear with "an educational package".

The theory is that knowledge reduces anxiety. There is good evidence that many patients who actually have cancer are empowered by accurate information (sensitively delivered), and that knowing what is happening and being able to participate in treatment decisions has enormous psychological benefits. But do patients benefit from knowing they are at small risk of cancer?

In the South-West region alone, nearly 12,000 women have a mildly abnormal smear each year. When retested six months later, 40 per cent (5,000) of these women will have a completely normal smear. In 1992, the NHS Cervical Screening Programme decided that instead of referring all women with mildly abnormal smears for immediate colposcopy (legs in styrups, cervix under a microscope, small biopsy), it would be better to "place them under surveillance" for six months. In effect, the policy for a mildly abnormal smear is to do nothing for six months and then repeat the smear. "You mean you're just going to leave it alone?" Cue mass panic.

The educational intervention was designed to lower anxiety by providing information and diagrams to give both knowledge and a sense of perspective. "An abnormal smear test does not mean cancer. It is just a risk factor. Likewise, smoking does not mean you'll get lung cancer. It just increases your risk of it."

Women are then invited to express their beliefs about what their abnormal smear means and to have them gently corrected. The use of population diagrams gets this nicely in perspective and the package concludes by saying: "For many women, abnormal cells go away on their own, thanks to your body's immune system. To check whether this has happened, you should have another smear in six months. If your next test is normal, you will need to have a smear test carried out more frequently for a while. If your test is still the same, you will be offered some minor treatment. We know that women worry far too much about a mildly abnormal smear test. We hope this information has made you feel better."

Fine sentiments, but what about the results? Two hundred and forty women with mildly abnormal smears were randomised into two groups, one receiving the educational package, one not. On the plus side, those women who had the package were found to have more knowledge about mildly abnormal smears, and were glad of it. But, alas, they were no less anxious than the package- free women.

So, knowledge is power but it doesn't stop you worrying. A rather depressing conclusion. My guess is that there are plenty of situations in medicine where knowledge does decrease anxiety - most notably when you've actually got something to worry about. Once a definitive diagnosis is made, knowledge is the key to planning your future and getting as much control back as you can.

But all cervical screening serves to do is peddle uncertainty, the one thing we all hate. The package was so clear that it was immediately obvious that screening isn't very accurate, that an abnormal smear is rarely anything to worry about but we've sown the seeds of Big C-phobia anyway. Now try not to worry about it.

The study also showed that the relationship between concern and knowledge is complex. This woman did not get the educational package: "I'm in the early stages of cancer. It is unlikely to be a false result, so I resent having to wait six months for treatment. The waiting is worse than the actual result. The not knowing - will I be here to see my children grow up, or do I start developing their self-sufficiency now?" This woman did: "My smear is 1 on a scale of 1 to 5. It could go back to normal. If it remains at 1 it would be lasered. I will have to have smears more often. It may be cut out, then therapy, then hysterectomy. It could then move somewhere else, and on to either continual treatment or death. I know the reality but my partner hasn't got a clue what it could mean for us, our relationship, our children's prospects."

Many cancer sufferers say the fear of cancer is worse than cancer. Planting the fear when the risk is small is a side-effect of all screening, and it's hard to say if it does more good than harm. What we can say about cervical screening is that when you smear a woman, it is not just her who is affected. You smear her whole family.