Study Finds Risk Associated With Regular Mammograms

In the U.S., breast cancer ranks second only to skin cancer as the most commonly diagnosed cancer in women, according to the Centers of Disease Control and Prevention. Even though the death rate for breast cancer has been in decline since the early 1990s, it still ranks as having the second highest death rate of any cancer in women other than lung cancer.

The high death rate still attributed to breast cancer is one of the reasons why health experts in the U.S. recommend that women undergo routine screenings. However, a recent study suggests that routine mammograms may inadvertently cause serious harm to women’s health.

The Best Intentions

A study conducted by researchers in Norway that was published in theAnnals of Internal Medicine found that one out of every four cancers detected over a decade through the use of routine mammograms were cancers that would not cause symptoms, spread, grow, or lead to death. However, despite the benign nature of these “overdiagnosed” cancers, most were treated with radiation, potent drugs, and surgery despite the fact that these cancers never presented a risk for making a woman ill.

As part of their findings, researchers determined that while doctors have known for some time that not all forms of breast cancer are potentially dangerous, they still don’t have an understanding on how many harmless breast cancers are being treated as a life-threatening illness.

Part of the reason doctors continue to treat all diagnosed breast cancer equally is because no reliable testing exists that can differentiate dangerous cancers from those that would otherwise not effect a person’s health. Since a every doctor has a moral and ethical obligation to treat any disease they find, doctors are compelled to treat all cancers as if they present a serious risk to the patient’s health rather than risk delaying treatment to see if the disease progresses.

The results of this study mark the most comprehensive attempt to determine exactly how many diagnosed cases of breast cancer were of non-invasive forms of the disease.

Estimating Overdiagnosis

Researchers began the study by examining the medical records of approximately 40,000 women diagnosed with invasive breast cancers in Norway shortly after the country began providing residents of certain regions regular mammograms.

Through a comparison of the cancers diagnosed in the women who were screened versus those who were not, researchers determined that anywhere between 15 and 25 percent of the cancers found using standard mammograms were non-invasive.

To place these numbers in context, researchers determined that for every 25,000 women between the ages of 50 to 69 who underwent regular mammograms for 10 years, 20 women would receive a diagnosis for a cancer that needed treatment, while six to 10 women would be overdiagnosed.

Researchers stress that the results of this study should serve as a warning that cancer screening doesn’t always equal prevention. The popular narrative that has formed in recent years that women must take the initiative to undergo regular breast cancer screening should also carry the caveat that screening could also lead to overdiagnosis.

Examining the study’s data, researchers at the Harvard School of Public Health concluded that the number of women in American to receive an overdiagnosis is probably higher than in a country like Norway because women in the U.S. start getting tested at an earlier age than women in Norway (screening in the U.S. generally begins when a woman is in her 40s vs. 50s in Norway), and also get tested more often (screening is done yearly in the U.S. vs. every two years in Norway).

Deciding Whether to Get Screened

In an effort to reduce the number of overdiagnosed cancers, many health experts in the U.S. have been pushing for the recommended age for a women to begin undergoing routine mammograms be pushed back to 50 instead of 40. However, despite this call to action, both the American College of Radiology and the American Cancer Society still recommend that women begin undergoing regular screenings after the age of 40.

When it comes to deciding the risks associated with routine screenings, women should consult with their doctor to determine whether the benefits of routine screenings outweigh the risks.