It's an old adage but it's nonetheless true: prevention is better than a cure. Following up on a range of previous studies, a recent European review of data shows that older women who attend mammography screenings for breast cancer significantly reduce their risk of dying from the disease.
A new international study based at Queen Mary University (QMU) in London shows that women aged 50 to 69 years who attend mammography screening on average reduce their risk of dying from breast cancer by 40 percent compared to women who are not screened. In the U.K., this relative risk means around eight deaths are prevented per 1,000 women who regularly attend screening, or five deaths prevented per 1,000 women invited to screening.
Stephen Duffy, professor of cancer screening at QMU, along with experts from 16 countries, looked at breast cancer screening on a global level and took into account routine screening programs — where all women of a certain age are invited to attend — and "opportunistic" screening services, which operate in countries without a set program. The researchers looked at the impact of a number of different breast cancer screening methods based on the results from 11 trials and 40 studies.
Their report — which confirms previous findings — suggests that women aged 50 to 69 years benefit most from breast cancer screening. However, several studies also showed a substantial reduction in the risk of death from breast cancer by inviting women aged 70 to 74 years for screening. This, the researchers say, contradicts the common understanding of the effectiveness of screening in older women. Unfortunately, limited evidence was found in favor of screening women in their forties.
Breast cancer is the most frequently diagnosed cancer in women worldwide. It is the second leading cause of cancer death in women in developed countries and the leading cause of cancer death in low and middle-income countries, where a high proportion of women are diagnosed in advances stages of the disease. Screening mammograms can detect problems before any lump or other problem can be felt — according to the American Cancer Society, it is at this stage that treatment is most effective.
In the several decades since screening was identified as an effective method in reducing deaths, mammography screening has increasingly been used in rich countries, though less so in the less well-off areas such as central and Eastern Europe. Most countries in Latin America have national recommendations or guidelines and in other low- and middle-income countries, breast cancer screening is promoted primarily by advocacy groups and periodic campaigns to promote breast awareness.
Though screenings greatly reduce the number of late-stage cases, in the past, concerns have been raised over the negative aspects of mammography screening — false-positive results, over-diagnosis and the possibility of radiation-induced cancer. The new review builds upon previous evidence suggesting that the potential benefits of breast screening outweigh the risks.
Duffy says: "This important analysis will hopefully reassure women around the world that breast screening with mammography saves lives. The evidence proves breast screening is a vital tool in increasing early diagnosis of breast cancer and therefore reducing the number of deaths." It is, he says, "vital we continue researching the most effective ways of screening women at high risk of breast cancer due to family history or genetic status. We need further evidence to fine-tune services offered to high risk women in terms of different screening methods, from an earlier age and possibly at shorter intervals."
"In the U.K., we are extremely fortunate to have the NHS [the publicly funded National Health Service] Breast Screening Programme where all women aged 50 to 70 years are invited to attend. Women invited to this service can be reassured the program is endorsed by internationally respected organizations and experts." The findings, which were published in the New England Journal of Medicine, were coordinated by the International Agency for Research in Cancer (IARC), the World Health Organisation's specialized cancer agency, and will contribute to an update of the IARC Handbook on breast cancer screening, last published in 2002.
Although the figures are encouraging and greatly convincing on the effectiveness of screening, Duffy remains pragmatic: "Despite evidence that mammography screening is effective, we still need to carry out further research on alternative screening methods, such as the promising 'digital breast tomosynthesis;' a newly developed form of 3-D imaging which could potentially improve the accuracy of mammography in coping with more dense breast tissue." Tomosynthesis is a potentially revolutionary method of examination designed to vastly improve analysis while making the experience less unpleasant for the patient — something of key importance if attendance figures are to rise.
There is, after all, something important to note in the figures. Though the reduction of risk stands at 40 percent for those attending, for all those invited to attend, it is 23. This means simply that a very large percentage of those invited don't make an appointment. The rerasons behind this discrepancy are surely of the utmost importance. If the greatest number of lives helped and even saved by the new technologies is to be reached, some investment of thought must also be put into exactly what it is that is keeping women from attending. It's a vital question when, as the research so clearly suggests — and as that other old adage says — 80 percent of success is just showing up.