A European study has found that for every 1,000 women between the ages of 50 and 70 who get a mammogram every 2 years, seven to nine lives are saved. For the same number of women, there would be four cases of overdiagnosis – a breast cancer is found that would have otherwise never been detected during a woman’s lifetime.
The study was published in the September 2012 issue of the Journal of Medical Screening. Read the abstract of “Summary of the evidence of breast cancer service screening outcomes in Europe and First estimate of the benefit and harm balance sheet.”
The value of routine screening mammograms was questioned in November 2009 when the U.S. Preventive Services Task Force (USPSTF) recommended that routine screening mammograms for women with an average risk of breast cancer should start at age 50 instead of age 40. The recommended changes were very controversial and were not universally adopted.
Since that time, the American Medical Association, the American College of Obstetricians and Gynecologists, the American College of Radiology, the American Cancer Society, the National Cancer Institute, and the National Comprehensive Cancer Network all have issued guidelines saying that all women should be eligible for screening mammograms starting at age 40.
Because of the USPSTF recommendations and other reviews questioning the value of screening mammograms, doctors in Europe formed the Euroscreen network to review studies on mammograms and develop a “balance sheet” on the pros and cons of mammograms. This balance sheet could be used by women to help them decide whether to get a mammogram, as well as by policy-makers and doctors. It’s important to know that this study didn’t include women in their 40s, so it doesn’t really add new information to the debate the USPSTF started.
To create the balance sheet, the researchers first figured out breast cancer risk among European women between the ages of 50 and 80 from 1985 to 1986, before routine screening was implemented. They found that about 6.7% of women would be diagnosed with breast cancer and 3% would die from the disease:
- 17 women out of 1,000 women between the ages of 50 and 70 would die from breast cancer
- 13 women out of 1,000 women between the ages of 70 and 80 would die from breast cancer
The researchers then calculated that out of these 30 deaths, 19 could have been prevented by screening mammograms. The researchers also found that 14 women would need to have a screening mammogram for one case of breast cancer to be diagnosed, and between 111 and 143 women would need to have a screening mammogram to save one life.
For every 1,000 women screened every 2 years from age 50 to age 69 and followed to age 79:
- seven to nine lives would be saved
- there would be four cases of overdiagnosis
- 170 women would have a false positive result and have to have another mammogram or non-invasive test
- 30 women would have a false positive result and have to have a biopsy or other invasive test
False positive results from screening mammograms have helped fuel the debate about the value of breast cancer screening. When a mammogram shows an abnormal area that looks like a cancer but turns out to be normal, it’s called a false positive. Ultimately the news is good: no breast cancer. But the suspicious area usually requires follow-up with more than one doctor, extra tests, and extra procedures, including a possible biopsy. There are psychological, physical, and economic costs that come with a false positive.
The researchers did point out that they weren’t sure how much DCIS diagnoses might be contributing to the number of cases overdiagnosed. DCIS is the most common form of non-invasive breast cancer. DCIS is called "non-invasive" because it hasn’t spread beyond the milk duct into any normal surrounding breast tissue. DCIS isn’t life-threatening, but having DCIS can increase the risk of developing an invasive breast cancer later on. Because more women are being screened, more cases of DCIS are being diagnosed. It’s not clear if the increase in DCIS cases is being offset by fewer cases of invasive cancer. More research is needed to better understand how DCIS diagnoses are affecting screening outcomes.
If you're 40 or older and have an average risk of breast cancer, yearly screening mammograms should be part of your healthcare. If your breast cancer risk is higher than average, you should talk to your doctor about a more aggressive breast cancer screening plan that makes the most sense for your particular situation.
There's only one of you and you deserve the best care possible. Don't let any obstacles get in the way of your regular screening mammograms:
- If you're worried about cost, talk to your doctor, a local hospital social worker, or staff members at a mammogram center. Ask about free programs in your area.
- If you're having problems scheduling a mammogram, call the National Cancer Institute (800-4-CANCER) or the American College of Radiology (800-227-5463) to find certified mammogram providers near you.
- If you find mammograms painful, ask the mammography center staff members how the experience can be as easy and as comfortable as possible for you.
For more information, visit the Breastcancer.org Mammograms pages.