Screening can be harmful.
Not all breast cancers cause death or disease during a woman’s lifetime, so this type of breast cancer does not need to be detected or treated.
It is often difficult to decide whether to participate in screening. Not all screenings are useful, and most are harmful. Before having any screening, you may want to talk to your doctor about screening to understand the dangers of screening and to see if screening has been shown to reduce the risk of death from cancer.
The dangers of mammography include the following:
Screening may give a false-positive result.
Screening may indicate an abnormality even in the absence of cancer. False-positive results (suggesting cancer but not actually having cancer) usually lead to additional tests (such as tissue biopsies), which are also risky.
When breast biopsy results are abnormal, consultation with another pathologist may be more helpful in the diagnosis of breast cancer.
Most abnormal results are not ultimately cancer. False-positive results are more common in women who are:
First mammogram screening is more likely to be a false positive than subsequent screenings. For every 10 women who receive only one mammogram, one woman is a false positive. The more mammograms a woman receives, the higher the probability of a false positive. Combining the results of previous mammograms and analyzing them in comparison with current results can reduce the risk of false-positive results.
The radiologist’s skill can also affect the probability of a false-positive result.
False-positive results can lead to more testing and trigger anxiety.
If the mammogram results are abnormal, more tests may be done to diagnose the cancer. During the diagnosis process, women can become anxious. Even if it is a false positive and the final diagnosis is not cancer, such results can lead to days or even years of anxiety.
Many studies have shown that women who feel anxious about a false-positive result are more likely to have regular breast screenings in the future.
False-negative results may delay diagnosis and treatment.
Screening results may show normal results even though breast cancer is present. Call this a false-negative result. A woman who has a false-negative result may delay seeking medical care, even if she has developed symptoms. Mammograms miss about one in five cancers.
False-negative results are more common in women who are:
When women find breast cancer, they usually take treatment. However, treatment may have side effects and may not improve health or extend life.
Some breast cancers found by mammography screening may never cause health problems or be life-threatening. The detection of these cancers is called overdiagnosis. When these cancers are detected, treatment may lead to serious side effects and will not extend life or improve health.
Mammogram screening exposes the breast to low doses of radiation.
High radiation doses are a risk factor for breast cancer. The radiation dose from screening mammography is very low, and women who start screening mammography after age 50 have a very low overall dose of mammography radiation. Women with large breasts or implants may receive a slightly higher dose of radiation during mammography screening.
There may be pain or other discomfort during the mammogram.
During a mammogram, the breast is placed between two splints. Putting pressure on the breast helps to get a better picture of the mammogram. Women may experience pain or other discomfort during a mammogram. The degree of pain may depend on the following factors:
Talk to your doctor about your breast cancer risk and your need for screening.
Talk to your doctor or other health care practitioner about your breast cancer risk, whether you need to be screened, and the benefits and harms of screening. After weighing the pros and cons, you should be involved in the decision about whether you need to be screened. (For more information, see PDQ’s “Cancer Screening Overview” summary)