Friday 8 December 2006
A ten year trial in which women between the ages of 40 and 50 were invited for annual breast screening did not show a significant reduction in breast cancer mortality.
The report by researchers at The Institute of Cancer Research is published today in the Lancet*. The trial was funded by Cancer Research UK, the Medical Research Council and the Department of Health. It involved around 160,000 women, of whom a third received annual screening invitations and two-thirds usual medical care.
The trial was the first of its kind to invite only women of 40 or 41 at the start of the trial to ensure all results were based solely on screening before age 50. Currently, when women reach the age of 50 they are invited for screening every three years by the NHS Breast Screening Programme.
The researchers estimated that screening from age 40 could save four lives for every 10,000 women screened. But it was reported that the benefit of screening women in their 40s needs to be balanced against possible negative considerations such as increased radiation exposure – which can contribute to breast cancer risk, and recalling women who do not have cancer for further tests – leading to anxiety and resulting in higher financial costs for the screening programme.
Of those women invited for the first screening 68 per cent attended. But the figure fell in later rounds, partly due to women moving away from the study areas. This led scientists to conclude that the potential benefits of screening the under 50s could be greater than that observed.
This study used two X-ray views of the breasts at the first screen and a single view subsequently. Nowadays, the standard procedure in the NHS screening programme is to take two views at all screens because it improves screening quality and increases the number of lives saved, But it also involves higher costs and a greater radiation dose to the woman screened.
Dr Sue Moss of The Institute of Cancer Research and lead author of the study, said: “The results of this study are consistent with similar studies which have included women under age 50 years at entry but in which some of the screening will have taken place at older ages.
“Longer follow-up of this trial will provide further information. It is important that all the potential advantages and disadvantages of screening are taken into account when considering any changes in policy.”
Professor John Toy, medical director of Cancer Research UK, said: “This paper shows no definitive evidence presently for women in their 40s to be included in the NHS Screening Programme. More years of follow-up, however, might reveal a benefit.
“We encourage women of all ages, and particularly older women in whom breast cancer is more common, to be breast aware and to see their doctor straight away if they notice any change in their breasts.”
*Lancet 2006: 368;2053-60
For further information please contact:
The Institute of Cancer Research Press Office
020 7153 5359 / 07788 427 856
Notes to editors:
- The National Breast Cancer Screening Programme invites women between the ages of 50 and 70 for breast screening every three years. 1.48 million women are screened each year and latest figures from the Breast Cancer Advisory Committee report that screening saves 1400 lives a year.
- Age is the most important risk factor for breast cancer. More than 80 per cent of all breast cancer cases are diagnosed in women over 50.
- There are around 41,700 cases of breast cancer diagnosed in the UK each year and 12,350 deaths.
- Among women aged between 40 and 49 there are 5,780 cases of breast cancer diagnosed each year and just over 1,000 deaths.
- Women’s risk of breast cancer according to age:
- By age 30: 1 in 1,900
- By age 40: 1 in 200
- By age 50: 1 in 50
- By age 60: 1 in 23
- By age 70: 1 in 15
- Over a lifetime: 1 in 9
A history of breast cancer in the family puts women at increased risk particularly if a close relative had breast cancer before the age of 50 or if two or more close relatives have been affected.
Starting periods at a younger age or having a late menopause increases risk.
Hormone replacement therapy increases the risk of breast cancer. Risk increases the longer a woman takes it and decreases gradually after she stops taking it.
Taking oral contraceptives may cause a small increase in risk but this gradually returns to normal once a woman stops taking them.
Being overweight after the menopause increases a woman’s risk of breast cancer as body fat affects hormone levels.
Drinking alcohol can increase the risk of breast cancer. The more a woman drinks each day the greater her risk.
The longer a woman breast-feeds her children, the lower her risk of breast cancer.
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