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Australians are increasingly being diagnosed with cancers that will do them no harm if left undetected or untreated.
A news article: Patients suffer invasive treatments for harmless cancers
The study itself: Estimating the magnitude of cancer overdiagnosis in Australia
Not a criticism of the paper itself, but of the news release: I think the headline is very poorly worded and can spread dangerous misinformation.
Cancer by definition 1 is harmful and can spread to other places in the body. There's no such thing as a "harmless cancer". I think the university PR team mixed up the term "tumor" (i.e. abnormal cell growth) and cancer (i.e. cell growth that spreads to other parts of the organism). The paper itself never says "harmless tumor" but describe at length "cancer overdiagnosis", which is perfectly reasonable. A tumor is not necessarily a cancer, but a cancer is often found in tumor. You can be misdiagnosed with cancer (i.e. the guy think you have cancer but you have not), but you cannot have a harmless cancer.
1 see Hallmarks of Cancer 1 and 2
It may seems a petty nitpick but I think the difference is crucial. I would be like conflating a bicycle and motor cycle.
I'm not so sure about that. Look at this sentence in the first paragraph of the paper:
They're clearly talking about actual cancers, and they are stating that some of those cancers would not cause symptoms or harm if untreated.
It's possible the error in terminology occurs in the paper itself. Maybe they've used the word "cancers" when they meant "tumours" - and the news release has just used the terminology from the paper.
We know that prostate cancer has a few different forms, but mostly it's a cancer that people die with, not of. We call it prostate cancer because it is cancer. The over-testing, over-diagnosis, and over-treatment of prostate cancer causes harm (impotence and incontinence are side effects of treatment) and importantly does not save life.
This is not some fringe view -- it's mainstream understanding.
https://www.nature.com/articles/s41568-019-0142-8
See this, which recommends stopping calling some things cancer. These things are cancer, but that word causes harm because people want to take action. https://www.bmj.com/content/362/bmj.k3528