Mammograms May Cause Overdiagnosis Of Breast Cancer
November 23, 2012

Researchers Find Overdiagnosis Of Breast Cancer With Mammograms

Connie K. Ho for — Your Universe Online

A new study published in the New England Journal of Medicine that looked at three decades of mammogram screenings finds that as much as a third of cancer diagnosed by routine mammograms may not be life-threatening.

The study was conducted by Dr. H. Gilbert Welch, a researcher at the Dartmouth Medical School, along with Dr. Archie Bleyer, a researcher at St. Charles Health System and Oregon Health & Science University. In the study, the researchers utilized data pooled from the Surveillance, Epidemiology, and End Results from 1976 to 2008. They wanted to look at trends from early stage breast cancer and late-stage breast cancer for women who were ages 40 and up.

In particular, mammograms are beneficial when they are done earlier and can detect life-threatening disease at a curable stage. The use of screening mammography has been related to double the number of cases of early-stage breast cancer, specifically increasing from 112 to 234 cases per 100,000 every year; this is an uptick of 122 cases for every 100,000 female. On the other hand, the number of late-stage cancer cases has reduced by eight percent, specifically from 102 to 94 cases for every 100,000 female.

"You see with mammography a dramatic increase in early-stage disease, but you don't see much compensatory decrease in late-stage disease. That means you are finding a whole lot of early cancers that were never destined to become late-stage," commented Dr. Gilbert Welch, a researcher at The Dartmouth Institute for Health Policy & Clinical Practice who has studied overdiagnosis in his research, in a report by Reuters.

However, based on these findings, the researchers concluded that there was an overdiagnosis of breast cancer over the last 30 years and that over one million women may have been overdiagnosed with breast cancer. In particular, the overdiagnosis of breast cancer in 2008 was about 31 percent of all the breast cancers diagnosed that year. These patients were exposed to the difficulty of breast cancer diagnosis and the aftermath that comes along with it, including procedures like chemotherapy, hormonal therapy, radiation therapy, and surgery.

"We're coming to learn that some cancers – many cancers, depending on the organ – weren't destined to cause death," remarked Dr. Barnett Kramer, an expert on screening at the National Cancer Institute, in an Associated Press (AP) article. "Once a woman is diagnosed, it's hard to say treatment is not necessary."

The researchers note that the decline in the breast cancer rate is as a result of factors like improved treatments, as opposed to early diagnosis through screenings.

As a result of this study, the question of the advantages of breast cancer screenings has been raised.

“These are major medical interventions and they´re certainly not something you would want to undergo if you didn´t need to,” Welch, the study´s co-author, told the Washington Post.

The researchers noted that women should be given a more balanced message regarding mammograms, letting them know the benefits and drawbacks of the screening then allowing them to make their own decision.

“We need to start telling the truth,” remarked Welch in the Washington Post article. “We´ve promoted this as if it's the most important thing a woman can do for her health“¦ And the truth is that it´s a really close call.”

On the other hand, supporters of mammograms have looked at the study and argued that, while the screenings are not free of errors, they provide more advantages than disadvantages.

"It points out issues that many if not all experts agree on, but the degree of the number of women have been impacted and the true impact of the negative side of mammography is something that other researchers would disagree with," explained Dr. Len Lichtenfeld, the deputy chief medical offer at the American Cancer Society, in the Reuters article.

The American College of Radiology Quality and Safety Commission has also brought up concerns on the study´s methods and questioned the data utilized in the project.

“It stuns me that this got through peer review,” mentioned Debra L. Monticciolo, a physician and chair of the commission, in the Washington Post article.

The study comes at a particular interesting time, as there have been past debates on the role of mammograms in the treatment and diagnosis of breast cancer. According to, the U.S. Preventive Services Tasks Force stopped advising mammograms for women in their 40s three years ago due to the higher number of false findings. There was also a finding of overdiagnosis from prostate cancer screenings that led the same task force to advise against the use of prostate specific antigen (PSA) blood test.