SCREENING FOR BREAST CANCER

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Breast cancer is one of the most important medical problems in the United Kingdom. There are almost 25,000 new cases every year and 15,000 deaths. Breast cancer accounts for 5 per cent of all deaths in women in the United Kingdom and is the commonest cause of death of women in middle age. The United Kingdom has almost the highest breast cancer mortality of any country which keeps records.

Breast cancer occurs in an organ which is easily examined. When the cancer is small it can be removed without much surgical damage to the breast. This would suggest that early diagnosis of the kind achieved by screening might result in a useful outcome in chat the cancer would be easily treated and the patient might be readily cured. However, we have already discussed the reasons for caution in believing that early diagnosis would necessarily lead to cure and it has required many decades of work to establish the curative potential of screening in breast cancer.

The evidence that screening can lead to an increased cure rate in breast cancer and reduce the overall mortality in the population is now very strong. Three countries (the United States, Sweden and Scotland) have performed trials in which a population of women were either screened or not according to the study design. The first study was carried out in New York using methods of clinical examination and breast X-rays (mammograms) and screening women between forty and sixty-four years of age every year. The second was carried out in Sweden and used mammography alone in women over the age of forty every eighteen months to three years. Both studies showed a reduction in mortality of about 30 per cent compared to mortality in the control group. It remains difficult to be precise about the size of the benefits. In the age group 50-69 years, the deaths from breast cancer are probably reduced by between 20 and 30 per cent if screening is introduced to the population. If an individual woman of this age goes for screening her personal risk of dying from breast cancer in the next ten years may be reduced by more than this – perhaps 40 per cent. Slightly less rigorous studies have been carried out in Italy and the Netherlands using the case-control method. They all used mammography but the ages of patients studied differed somewhat. Screening was at between one- and four-yearly intervals. The studies also showed a reduction in mortality compared to that of the unscreened population. All this evidence is pretty compelling. Screening for breast cancer is feasible and can be effective.

This is not all that we need to consider. We have to ask who should be screened, how often they should be screened and by what technique. The evidence suggests that the benefits are greatest for women over the age of fifty. The benefit of screening women below fifty is uncertain and further research will be necessary before screening can be firmly recommended for women under that age. Mammography seems to be a necessary part of a successful screen. As we shall explain, breast examination alone is insufficient. It seems as though screening has to be carried out at least every three years.

The obvious screening test is for a doctor or other healthcare professional to examine the breast. It is difficult by this method to pick up cancers that are smaller than about I cm and many lumps that are not cancer will be detected. Examination by itself is therefore potentially rather insensitive and most evidence to date suggests that this approach is insufficient. Mammography is a technique that uses very small doses of X-rays to produce a picture of the breast which is much more sensitive than physical examination and can give useful information about whether the abnormalities seen are due to a cancer or are not. The radiation dose is tiny and mammography is at present the most sensitive technique for finding a breast cancer in screening.

In 1988 Health Authorities in the United Kingdom began phasing in the National Breast Screening Programme. A nation-wide service is being established to apply mammography every three years to women aged between fifty and sixty-four years. This is a huge and expensive undertaking but it can potentially reduce the death rate from breast cancer by one quarter in this age group. There remain arguments about the cost-effectiveness of the programme and the possible anxieties provoked by screening. Nevertheless it is a major health initiative and deserves support.

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SCREENING FOR BREAST CANCERBreast cancer is one of the most important medical problems in the United Kingdom. There are almost 25,000 new cases every year and 15,000 deaths. Breast cancer accounts for 5 per cent of all deaths in women in the United Kingdom and is the commonest cause of death of women in middle age. The United Kingdom has almost the highest breast cancer mortality of any country which keeps records.Breast cancer occurs in an organ which is easily examined. When the cancer is small it can be removed without much surgical damage to the breast. This would suggest that early diagnosis of the kind achieved by screening might result in a useful outcome in chat the cancer would be easily treated and the patient might be readily cured. However, we have already discussed the reasons for caution in believing that early diagnosis would necessarily lead to cure and it has required many decades of work to establish the curative potential of screening in breast cancer.The evidence that screening can lead to an increased cure rate in breast cancer and reduce the overall mortality in the population is now very strong. Three countries (the United States, Sweden and Scotland) have performed trials in which a population of women were either screened or not according to the study design. The first study was carried out in New York using methods of clinical examination and breast X-rays (mammograms) and screening women between forty and sixty-four years of age every year. The second was carried out in Sweden and used mammography alone in women over the age of forty every eighteen months to three years. Both studies showed a reduction in mortality of about 30 per cent compared to mortality in the control group. It remains difficult to be precise about the size of the benefits. In the age group 50-69 years, the deaths from breast cancer are probably reduced by between 20 and 30 per cent if screening is introduced to the population. If an individual woman of this age goes for screening her personal risk of dying from breast cancer in the next ten years may be reduced by more than this – perhaps 40 per cent. Slightly less rigorous studies have been carried out in Italy and the Netherlands using the case-control method. They all used mammography but the ages of patients studied differed somewhat. Screening was at between one- and four-yearly intervals. The studies also showed a reduction in mortality compared to that of the unscreened population. All this evidence is pretty compelling. Screening for breast cancer is feasible and can be effective.This is not all that we need to consider. We have to ask who should be screened, how often they should be screened and by what technique. The evidence suggests that the benefits are greatest for women over the age of fifty. The benefit of screening women below fifty is uncertain and further research will be necessary before screening can be firmly recommended for women under that age. Mammography seems to be a necessary part of a successful screen. As we shall explain, breast examination alone is insufficient. It seems as though screening has to be carried out at least every three years.The obvious screening test is for a doctor or other healthcare professional to examine the breast. It is difficult by this method to pick up cancers that are smaller than about I cm and many lumps that are not cancer will be detected. Examination by itself is therefore potentially rather insensitive and most evidence to date suggests that this approach is insufficient. Mammography is a technique that uses very small doses of X-rays to produce a picture of the breast which is much more sensitive than physical examination and can give useful information about whether the abnormalities seen are due to a cancer or are not. The radiation dose is tiny and mammography is at present the most sensitive technique for finding a breast cancer in screening.In 1988 Health Authorities in the United Kingdom began phasing in the National Breast Screening Programme. A nation-wide service is being established to apply mammography every three years to women aged between fifty and sixty-four years. This is a huge and expensive undertaking but it can potentially reduce the death rate from breast cancer by one quarter in this age group. There remain arguments about the cost-effectiveness of the programme and the possible anxieties provoked by screening. Nevertheless it is a major health initiative and deserves support.*126\194\4*

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