Mammograms are tests used to screen for breast cancer, but they have some limitations. They are not 100% accurate and can sometimes miss detecting breast cancer or show things that are not cancerous but still require further testing.
Elizabeth Cohen talks to the American Cancer Society’s chief medical officer about the downsides of getting mammograms at age 40 instead of 45.
False-negative results:
Sometimes a mammogram may appear normal even when breast cancer is present. It can miss about 1 in 8 breast cancers. Women with dense breasts are more likely to have false-negative results. This can give a false sense of security, making them believe they don’t have breast cancer when they actually do. If you experience new breast symptoms, it’s important to see a doctor, even if your recent mammogram was normal. Additional tests may be needed to investigate further.
False-positive results:
A false-positive mammogram may show an abnormality even when there is no breast cancer. This often leads to additional tests like diagnostic mammograms, ultrasound, or even a breast biopsy to confirm if there is any cancer. False-positive results are more common in younger women, those with dense breasts, previous breast biopsies, a family history of breast cancer, or those taking estrogen. Over a 10-year period, about half of women receiving annual mammograms will have a false-positive finding at some point. This can cause anxiety and unnecessary tests, which can be time-consuming, expensive, and uncomfortable.
Mammograms might not be helpful for all women:
The benefits of mammograms depend on a woman’s overall health. If a woman has serious health problems or a short life expectancy due to conditions like heart, kidney, liver, or lung disease, finding breast cancer early may not necessarily extend her life. It is important for women with such conditions to discuss with their doctors whether they should continue having mammograms. Age alone should not be the sole reason to stop regular mammograms, as guidelines emphasize.
Overdiagnosis and overtreatment:
Mammograms can detect breast cancers that need to be treated, including invasive breast cancer and ductal carcinoma in situ (DCIS). However, some of the cancers found on mammograms may never cause harm or spread. This is called overdiagnosis. Doctors cannot always differentiate between cancers that are life-threatening and those that would never cause problems. Consequently, all breast cancers are usually treated, which can result in overtreatment. Some women receive unnecessary treatment, exposing them to the side effects of cancer treatment even when it wasn’t truly needed. Overdiagnosis is estimated to occur in a range of 1% to 10% of breast cancers.
Radiation exposure:
Mammograms use x-rays, which expose the breasts to radiation. Although the amount of radiation from each mammogram is low, it can accumulate over time.