Cancer Overdiagnosis

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Our blog on overdiagnosis

Overdiagnosis is a complicated issue. It is associated more often with certain types of cancer, usually because they are associated with types of screening that test people without symptoms. This makes it important when considering whether screening helps beat cancer and the balance of possible benefits and harms.

What is overdiagnosis?

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 would never have known they had cancer.


How does it happen?

Not all cancers behave in the same way - this is true even for cancers of the same type. Some will spread quickly, and others are so slow-growing they’ll never cause harm. It’s when these slower-growing harmless cancers are picked up that they’re said to be overdiagnosed. It can be risk of screening, where people without symptoms are tested for the disease.


Why is it important?

It is not yet possible to tell if an individual person’s cancer has been overdiagnosed when diagnosed, only retrospectively. This means same people will go through treatment, distress and potential side effects when they didn’t need to. Its important people are aware of overdiagnosis as a potential harm of screening.

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