7 May 2010
Screening mammography no benefit to women under 40
Women under the age of 40 are unlikely to benefit from mammography screening for breast cancer - even if they have a family history of the disease in close relatives, according to new research published in the Journal of the National Cancer Institute this week.
Mammograms are X-rays of a woman's breasts. When a mammogram is used to check for breast changes in women who don't have any breast symptoms, it's called a screening mammogram. When it is used to check for breast changes in women who do have breast symptoms, it's called a diagnostic mammogram.
Screening mammograms have been shown to be effective at detecting breast cancer in older women, and so are usually only offered to women aged 40 or 50 and above, depending on the provider. The current study aimed to find out whether mammograms are also beneficial for women younger than 40.
The study looked at data from more than 100,000 women in the USA, who were aged between 18 and 39 when they had their first mammogram. This included both screening and diagnostic mammograms. Women with abnormal mammograms were referred for further tests to confirm whether they had breast cancer. The researchers then looked at the results of these additional tests to determine how accurate the mammogram was.
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Dr Peter Mace, Assistant Medical Director, Bupa |
This study has shown that for women under the age of 40, having a mammogram isn't useful and is likely to lead to more harm than good. 
The vast majority of screening mammograms (73,335) were carried out in women aged 35 to 39. Of this group, approximately one in eight of the mammograms were abnormal and needed further tests to exclude cancer. However, very few of these women (just over one in 100 of those with abnormal mammograms) were actually found to have breast cancer, meaning that for the majority, the additional investigations were unnecessary. No women under the age of 25 were found to have breast cancer.
Based on the findings of this study, for every 10,000 women aged 35 to 39 who have a screening mammogram, 1,250 would be given a 'false positive' result - which means they have a positive screening test, but don't actually have cancer and may therefore undergo unnecessary tests and treatment; 16 women would be correctly identified as having cancer and may go on to receive treatment that they need; and five would be given a 'false negative' result, which means that they have breast cancer, but it is not be picked up by the mammogram.
The accuracy of mammography as a screening test was not any better when the researchers looked at just those women who had a family history of breast cancer in close relatives. However, the researchers did not have data on whether the women carried a faulty gene for breast cancer, which can increase the risk considerably. Therefore, it was not possible to answer the question as to whether mammography may be more accurate in these high-risk groups. The study did indicate that mammography was more useful when carried out as a diagnostic test in women who had symptoms.
Dr Peter Mace, Assistant Medical Director at Bupa, commented: "Mammography is a very useful test for women over the age of 40, with reports suggesting that it helps to save the lives of more than 1,000 women every year in the UK. However, this study has shown that for women under the age of 40, having a mammogram isn't useful and is likely to lead to more harm than good. Not only is there the worry and anguish that a 'false positive' result can give, but also the potential harm from radiation and from further unnecessary, invasive tests.
"My advice to young women who are concerned about their risk of breast cancer is to be 'breast aware' - be familiar with the usual look and feel of your breasts. Remember that breast cancer under the age of 40 is rare and very rare under age 30, but if you do notice any changes in your breasts, it's important not to ignore them and to seek advice from your GP.
"Currently at Bupa we offer screening mammograms for our customers over 40 years old. We will continue to review medical research in this area to get the best evidence to help improve our customers' health."
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Related Bupa products and services
Book an appointment for a thorough breast health check from Bupa, including mammography if you're over 40.
- Find out more about the Bupa Breast Health check
- Request an appointment
- Call us on 0845 600 3458
Related information
- Breast awareness - health factsheet
- Breast cancer - health factsheet
- Breast lump investigation - health factsheet
- Mammography if you don't have breast symptoms - health factsheet
- Mammography if you have breast symptoms - health factsheet
Read the study
Yankaskas BC, Haneuse S, Kapp JM, et al. Performance of first mammography examination in women younger than 40 years. J Natl Cancer Inst 2010. doi: 10.1093/jnci/djq090
