Screening Mammography and Overdiagnosis: How to Explain the Controversy to Patients?

Laurie R. Margolies, MD; Saurabh Jha, MBBS, MRCS; Daniel B. Kopans, MD


January 20, 2017

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Laurie R. Margolies, MD: Hello. I am Laurie Margolies, associate professor of Radiology at Mount Sinai Hospital. I hope you had the chance to watch our video with Drs Jha and Kopans about breast cancer screening. Here are a few additional discussion points that may be of interest.

Given that there is disagreement about the age at which to begin screening and whether overdiagnosis is occurring and how often, how do we explain that to our patients? How do we tell patients that it is a population issue and we cannot tell if it relates to them? Dr Kopans, let us start with you.

Daniel B. Kopans, MD: You provide patients with accurate information. The problem is that physicians have been derelict in critically reviewing publications that have been accepted when the science is not behind them. In medical school, we are taught to critically read papers. When we get out of medical school, most of us read the abstracts. Then we assume that because it passed peer review, the abstract must be correct. I think you would probably be the first to agree with me that that is simply not true.

Doctors have to read papers. It is very hard for primary care doctors to take the time to go through all of the breast cancer screening papers. That is why they rely on supposed experts to advise them. I am one of the supposed experts. I am perfectly happy if people read papers themselves, understand the papers, and make decisions based on them. Most of them do not. Most of them are depending on the American College of Physicians, for example, to provide primary care doctors with guidelines. Radiologists rely on the American College of Radiology and Society of Breast Imaging.

You have to know that there are probably biases in those situations. Physicians need to be informed. If they don't understand it, they should admit that they don't understand it and send the patient to someone who does understand the data.

I will bring up one other point about overdiagnosis.[1,2] All of the studies to which you referred, suggesting that as many as 50% of patients are overdiagnosed, have been reviewed by epidemiologists. One of your colleagues reviewed all of those papers, and she and the group that reviewed them showed that the ones that suggested major overdiagnosis made major scientific errors, including not accounting for lead time and not accounting for breast cancer risk in the populations that were reviewed. Her review said that overdiagnosis is 10% at most and is probably as low as 0%.[3] The problem is that this idea of overdiagnosis has been given a life of its own based on no data.

Dr Margolies: Dr Jha, what do you think? It's a difficult question.

Saurabh Jha, MBBS, MRCS: I am going to quote Groucho Marx. He said, "Those are my principles, and if you don't like them... well, I have others." I have assumptions. If you don't like them, I have others.

I agree that the calculation for overdiagnosis is tricky, but it is not something that just came out of thin air and occupied breast cancer. We have seen that in thyroid cancer screening. If you look at what happened in South Korea, once they started doing ultrasound on patients, the papillary thyroid cancer rate went shooting high, like an exponential curve.

Thyroid is not breast, but the idea of cancer being a monolith is simply not correct. We decided not to talk about ductal carcinoma in situ (DCIS) because it is complicated, but the principles emanate from there as well. People are going for a watchful-waiting strategy based on that. I don't think we can completely put this issue under the rug.

Dr Kopans has made a valid point that the problem with overdiagnosis comes from the diagnoses of cancer pathologists. Complicating that with DCIS, they have interobserver variability. We think of pathologists as being the gold standard, but they disagree with each other. It is a vexing problem that can lead to overtreatment.

Imagine a woman's counterfactual in a parallel universe. She lives happily and dies at the age of 82 from a heart attack. Over here, she has a bilateral mastectomy from DCIS, and then she develops an infection and complications. That may not be the problem of radiologists, but it is still a problem of the screening.

The parsimonious thing to do would be to admit and not deny that mammography reduces cancer mortality, and to also say that there is a possibility of overtreatment if "overdiagnosis" is not the preferred term. Then, let women make up their own minds. It could very well be that the adherence to screening will not be reduced.

Dr Kopans: We are in complete agreement. Women should be given accurate information so that they can make up their own minds and make informed decisions. It does not stop at age 50. It starts when you start screening at age 40, and it goes all the way until a woman decides with her physician that the quality of her life is such that she can stop screening.

The problem that we are faced with is our false ideas that have taken on a life of their own based on misinformation. I hate to think of this: a woman who is going to get treated for her breast cancer and is killed in an automobile accident. That is clearly overdiagnosis.

Dr Jha: I used that example in my paper.

Dr Kopans: It would have been overtreatment. All of healthcare is overtreatment. We treat people with bacterial infections, lung infections. We treat them with antibiotics. Some get better on their own. We don't know who they are. Some will be made worse by the antibiotics and some might be killed by an anaphylactic response. Healthcare is imperfect. Breast cancer diagnosis and treatment is imperfect. But you don't pull the engine out of the car to prevent car accidents. You screen. You find cancers. Then you get better at how you make the diagnosis and treat them. Don't deny women the ability to have their lives saved.

Dr Margolies: This has been an absolutely fascinating discussion. I think we can all learn that screening mammography saves lives. There are considerable debates that will persist for many, many years.

Thank you for watching. Please be sure to tell us how you feel about this topic in the comments section of this video. We look forward to hearing from you.


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