Cancer Overdiagnosis

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See a more in-depth discussion on overdiagnosis on our blog

Our blog on overdiagnosis

Overdiagnosis is a potential harm of efforts to achieve earlier diagnosis, and particularly to the identification of disease in apparently healthy people – screening. It is a complex issue which is important to understand at a population level, but difficult to predict at an individual level.

It is one of the key considerations when weighing up the balance of benefits and harms associated with interventions such as cancer screening.

What is overdiagnosis?

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Overdiagnosis is the diagnosis of a cancer that wouldn’t have gone on to cause harm in a person’s lifetime, in other words, if the person hadn’t been tested (whether that’s screening or some other type of test), the person might never have known they had cancer, and would not have died from the disease.

How does it happen?

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Not all cancers behave in the same way - this is true even for cancers arising from the same part of the body. Some will spread quickly, and others are so slow-growing they’ll never be the cause of someone dying. It’s when these slower-growing harmless cancers are picked up that they’re said to be over diagnosed.

Why is it important?

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It is not yet possible to tell at the point of finding a cancer, if that particular cancer is a case of overdiagnosis, or if it is a cancer that could go on to cause harm or death if it’s not treated. This means some people will go through treatment, distress and potential side effects when they didn’t need to.

There is a lot of research happening to see if it might be possible to better identify which cancers need treating, and which ones don’t. In the meantime, it’s important people are aware of overdiagnosis as a potential harm of screening.

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