Breast Cancer Misdiagnosed in More Than 100 Cases: Study

A new study of mammograms conducted in Quebec found an alarming number of cases of breast cancer misdiagnosis. 

At least 109 instances of missed breast cancer were revealed by a survey of 22,000 mammograms according to the findings of the study, conducted by the Collège des médecins. As a result of the findings, the college made a number of recommendations that call for better mammogram oversight.

The survey looked primarily at mammograms conducted by one radiologist after fears arose that there may have been errors. The mammograms were taken between 2008 and 2010 at three clinics in Montreal and Laval. The radiologist involved with those cases has not worked in the field since October 2010, but health officials indicate that doesn’t mean there are not changes that still should be made.

“Our primary concern has always been to ensure that the women who had these mammograms are informed, supported and accompanied until they receive all the services and health care they need,” Dr. Louise Charbonneau, investigator for the Collège des médecins, said in a press release.

Experts who took part in the survey recommended that formal connections be established between mammogram screening centers, private clinics and referral centers in order to promote more monitoring, feedback and communication about the performance of screening centers and their radiologists. They also recommended that a board of four expert radiologists be created monitor mammograms across the entire territory of Quebec, and that all mammograms be available digitally to provide easier access when needed.

In addition to the mammograms, the survey also looked at about 500 CT scans and decided that 158 patients should have the scans redone.

Missing potential signs of cancer was not the problem that different researchers from Norway found in another breast cancer mammogram study. Instead they found doctors were overdiagnosing breast cancer in many cases, according to findings published this week in the Annals of Internal Medicine.

Breast cancer overdiagnosis occurs when a tumor is found that fills all of the laboratory criteria to be called cancer, but is not actually cancerous. The tumor does not grow and spread, and causes no harm. It can be removed and treated or left alone, but it is often impossible for a doctor to tell the difference.

According to the findings, 18-25% of cases of breast cancer found in women in Norway are overdiagnosed. That means that out of 2,500 women, six to 10 will be told they have breast cancer when all they have is a tumor that would do no harm if left alone. The researchers attributed the growth of such cases to mammogram screening programs put into place in that country gradually from 1996 to 2005.

In countries that have had mammogram screening programs that were more aggressive and have been in place longer, like the United States, the percentage of cases of breast cancer overdiagnosis could be much larger.

Doctors say women should still get screened and should still have breast masses investigated. While overdiagnosis does occur, the problem is that there is no way to tell, in a timely manner, which tumors are aggressive and which are not, so they should still be treated as though they are an aggressive form of cancer until a woman’s healthcare provider can determine otherwise.