Several youtubers have in recent years tried to raise awareness of one of the most innocently devious phenomena in modern medicine, a statistical bias that fools even most medical professionals, and it's related to the success of cancer treatment.
It is widely known and lauded that cancer survival rates have gone significantly up since the 1970's and earlier, which, according to these statistics, is a huge success story in modern medical science.
However, as many people (including medical professionals and researchers) have pointed out, this is actually a statistical anomaly, not an actual fact. Yes, life expectancy has genuinely gone up thanks to more modern cancer treatment, but not even nearly as much as these misguided statistics would indicate.
The main problem is that "surviving cancer" in these statistics is not measured by how many people were completely cured of cancer. One would think that that's precisely what they are looking at, but perhaps a bit surprisingly, it's not.
Indeed, cancer treatment is not considered a success if the person is completely cured of cancer. Instead, it's considered a success if the person lives at least 5 years after diagnosis.
There are many reasons why it's measured like that instead of "cancer completely disappeared", but the feeling of it being a bit asinine is very understandable.
So what's the problem? The problem is that life expectancy hasn't actually increased that much. What has improved is how early cancer is being detected, compared to the 1970's.
That indeed means that a lot of cancers are being detected much earlier, meaning that the amount of people who live at least 5 years after detection has increased, even though their actual life expectancy hasn't increased by much, if at all.
In other words, cancer patients aren't actually living any longer. It's merely that more people who live longer after diagnosis are being added to the statistics. This doesn't mean that the success of treatments has improved, it simply means that there's a sampling bias: A lot more people are now being included in the statistics that wouldn't have been included in the 70's (and these extra people are the ones who live the longest after diagnosis.)
This also has a negative side effect: More and more people who in the 70's and 80's would have been none the wiser and lived happily 5, 10, even 15 years more, are now being stressed and worried sick about having cancer, and subjected to treatments that might or might not prolong their lifespan somewhat.
Such a diagnosis can be psychologically devastating. Ironically, the extreme stress and depression that ensues might even shorten some people's lifespan from what it would have been if they had been oblivious to their condition. Extreme prolonged stress is not without its consequences.
Of course this doesn't mean people should not be screened for cancer. It's an extremely complicated problem with no easy solutions.
By the way, this statistical anomaly even has a name: The Will Rogers phenomenon.
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