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Why is Mammogram Advice Such a Moving Target?

Posted by Johnson Memorial Health on Jan 8, 2015

A mammogram is an x-ray of a breast. Screening mammograms are used to check for breast cancer in women who have no signs or symptoms of the disease. Diagnostic mammograms are used to check for breast cancer after a lump or other symptom has been found.

According to the National Cancer Institute, screening mammography can help reduce the number of deaths from breast cancer in women from 40-74. Because of this, annual mammograms have long been recommended for women over the age of 40.

However, in recent years, screening mammography has been the subject of some discrepancy.Thus, we ask the question, "Why is mammogram advice such a moving target?"


In order to get a clear picture of the debate, let's take a look at both sides of the issue.


Those against regular screenings do so because of the following: 

False-positive results

False-positive results occur when radiologists decide mammograms are abnormal but no cancer is actually present. False-positive mammogram results can lead to anxiety and other forms of psychological distress in affected women. The additional testing required to rule out cancer can also be costly, time consuming and can cause physical discomfort.

Overdiagnosis and overtreatment

Screening mammograms can find aggressive forms of cancer. However, they can also find cancers and cases of ductal carcinoma in situ (DCIS) that will never cause symptoms or threaten a woman’s life, leading to an overdiagnosis of breast cancer. Treatment of these latter cancers and cases of DCIS is not needed and leads to overtreatment, which exposes women unnecessarily to the adverse effects associated with cancer therapy. Because doctors often cannot distinguish cancers and cases of DCIS that need to be treated from those that do not, all are treated.

False-negative results

False-negative results occur when mammograms appear normal even though breast cancer is present. The main cause of false-negative results is high breast density. Because fibroglandular tissue and tumors have similar density, tumors can be harder to detect in women with denser breasts. False-negative results can lead to delays in treatment and a false sense of security for affected women. 

Radiation exposure

Mammograms require very small doses of radiation. The risk of harm from this radiation exposure is extremely low, but repeated x-rays have the potential to cause cancer. The benefits of mammography, however, nearly always outweigh the potential harm from the radiation exposure. Nevertheless, women should talk with their health care providers about the need for each x-ray. 


Those in favor of screening mammograms (including Johnson Memorial Health) claim that these annual screenings are valuable to women's health. And the American Cancer Society recommended in September 2014 that women over the age of 40 should have a mammogram annually and "should continue to do so as long as they are in good health."

These x-ray images make it possible to detect tumors that cannot be felt. Screening mammograms can also find microcalcifications (tiny deposits of calcium) that sometimes indicate the presence of breast cancer. Early detection of breast cancer with screening mammography means that treatment can be started earlier in the course of the disease, possibly before it has spread.

According to the U.S. National Library of Medicine, results from randomized clinical trials and other studies show that screening mammography can help reduce the number of deaths from breast cancer among women ages 40 to 74, especially for those over age 50. (Studies to date have not shown a benefit from regular screening mammography in women under age 40 or from baseline screening mammograms (mammograms used for comparison) taken before age 40.)

Here at Johnson Memorial Health, we have two mammography suites that perform over 325 procedures each month. We believe in this technology and are confident that the services we offer our patients are regularly saving lives.

We encourage all women to perform breast self-exams regularly and to be well-informed about the benefits and risks of mammography. It is an imperfect test, but it's one that we believe in. 

If you have questions regarding mammograms or breast health, contact our Breast Care Center for more information. 

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Topics: Mammogram