Article date: September 30, 2010
By Eleni Berger
Two new studies, one on women in their 40s and the other on women 50 and older, show that regular screening mammograms do help reduce deaths from breast cancer. Though the studies differ somewhat in their methods and specific findings, they ultimately support the American Cancer Society's recommendation that women get regular mammograms as an important part of a breast cancer screening plan.
Screening mammograms are done in women with no symptoms of breast cancer in order to find the disease early, when treatments are more likely to be successful. Most studies have found that regular screening with mammograms does help reduce the death rate from breast cancer, especially in older women. But there is disagreement in the medical community over when women need to start getting screening mammograms and how often they should have them.
The American Cancer Society recommends mammograms every year for women 40 and older who are at average risk of breast cancer (women at higher risk may need to start earlier or get additional tests). Some other groups, though, recommend starting mammograms at age 50 and/or having them every other year.
The new studies do not conclusively resolve these differences, but they do provide more insight into the benefits of screening mammograms.
Significant benefit for women in their 40s
The newest study, published Wednesday in the journal Cancer, looked at the effectiveness of screening mammograms for women in their 40s. Researchers from Umeå University in Sweden compared death rates from breast cancer in women who got screened and those who didn't between 1986 and 2005. The women were screened through a national program that offered mammograms every 18 months or 2 years to women in certain Swedish counties.
The death rate from breast cancer was 29% lower in the women who got mammograms compared to those who didn't. The benefit was greater in women age 45-49 than in those age 40-44.
Benefit smaller than expected for older women
The second study, published in the New England Journal of Medicine last week, looked at mammograms in women between the ages of 50 and 69. These women were offered mammograms every 2 years, as part of a national screening program in Norway. Those diagnosed were then treated with a coordinated approach by teams of specialists in their county of residence.
The researchers, from the Cancer Registry of Norway, Oslo, Harvard School of Public Health, and the Dana-Farber Cancer Institute in Boston, compared the death rate from breast cancer in women who were and were not screened after the national program was introduced (between 1996 and 2005). They also looked at breast cancer death rates before the program was in effect (1986-1995) to help determine how much screening (as opposed to improvements in treatment and other factors) contributed to the change.
These researchers also found that screening mammography reduced the death rate from breast cancer – but by only 10%, far less than expected. They say better treatment through the coordinated care teams likely accounted for most of the improvement.
Mammograms only part of ACS recommendations
Although these studies differ in their assessment of how effective breast cancer screening programs are, both do find a benefit from regular mammograms.
Nevertheless, mammograms aren't perfect; they can miss some cancers or find problems that turn out not to be cancer after further tests. For this reason, mammograms are only one part of the American Cancer Society's guidelines for the early detection of breast cancer. In addition to yearly mammograms, women 40 and older should also get a breast exam by a healthcare professional every year (women in their 20s and 30s should have a breast exam at least every 3 years).
Along with these recommended exams, women need to be aware of how their breasts normally look and feel and should report any changes to their doctor right away.
To read the American Cancer Society's complete recommendations for breast cancer screening, see the American Cancer Society Guidelines for the Early Detection of Cancer. To learn more about breast cancer, check out our Breast Cancer Detailed Guide and the other materials at www.cancer.org/breastcancer.
Citations: "Effectiveness of population-based service screening with mammography for women ages 40 to 49 years." Published online Sep. 29, 2010, in Cancer. First author: Barbro Numan Hellquist, MSc, Umeå University, Umeå, Sweden.
"Effect of Screening Mammography on Breast-Cancer Mortality in Norway." Published in the Sep. 23, 2010 New England Journal of Medicine. First author: Mette Kalager, M.D., Cancer Registry of Norway, Oslo.
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