National Breast Cancer Coalition

Overdiagnosis and Overtreatment

An estimated 30% of all breast cancer cases (both invasive and DCIS) are considered to be overdiagnosed and overtreated.1 Overdiagnosis, a downside of screening, is diagnosis of cancers that would not have presented within the life of the patient. Overdiagnosis is likely to increase with technological developments, including digital mammography, computer-aided detection and improved biopsy techniques. It is also driven by the patient's fear that cancer will be missed and the doctor's fear of litigation.2 Overtreatment can occur in two ways – either in overdiagnosis, where any treatment is unnecessary, or with the administration of more aggressive therapies than is necessary.3

For every 2,000 women invited for screening over a 10 year period, one will have her life prolonged and 10 healthy women, who would not have been diagnosed if they had not been screened, will be treated unnecessarily.4 The evidence of a mortality reduction from screening is conflicting and continues to be questioned by some advocates, scientists, policy makers and members of the public. In fact, the absolute risk of a woman dying from breast cancer is less than 1% without any screening. Looking at this another way, 995.6 out of 1,000 50-year-old women will not die of breast cancer within the next ten years. This number rises to 996 out of 1,000 with regular mammography screening.5

History has shown that once a treatment regimen is in place and becomes standard, it can take a long time to remove it from practice, even when scientific evidence no longer supports its use.6,7 Patient-centered care requires that removing a treatment from standard care should happen as quickly and routinely as adding a new one, once the evidence supports a change.

1.  Gotzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database Syst Rev. 2011;1:CD001877.

2.  Warren R, Eleti A. Overdiagnosis and overtreatment of breast cancer: is overdiagnosis an issue for radiologists? Breast Cancer Res. 2006;8(2):205.

3.  Paci E, Duffy S. Overdiagnosis and overtreatment of breast cancer: overdiagnosis and overtreatment in service screening. Breast Cancer Res. 2005;7(6):266-270.

4.  El-Tamer MB, Ward BM, Schifftner T, Neumayer L, Khuri S, Henderson W. Morbidity and mortality following breast cancer surgery in women: national benchmarks for standards of care. Ann Surg. May 2007;245(5):665-671.

5.  Welch HG. Screening mammography--a long run for a short slide? N Engl J Med. Sep 23 2010;363(13):1276-1278.

6.  Public Broadcasting System. 'Practice-Changing' Cancer Study Shows Lymph Node Surgery May Be Unnecessary PBS News Hour2011.

7.  Kleinman JC, Machlin SR, Madans J, Makuc D, Feldman JJ. Changing practice in the surgical treatment of breast cancer. The national perspective. Med Care. Dec 1983;21(12):1232-1242.