Someone mentioned this on another forum. I know I once read that the body can have cells turn cancerous, but the immune system clears them out or segregates the cells, and that this is not uncommon. But cells going cancerous daily seems very hard to believe, despite there being 100 trillion cells in the body and billions reproducing daily.
And what is the definition of cancer? Is it just any cell that reproduces without direction from the organism as a whole?
I’m not talking about ‘I’m going to die from this’ cancer obviously, I mean does a person daily experience having a few cells mutate into cancer, but the body fixes it before it becomes a problem?
This is a terrible cite, but I was once at a seminar where someone was working on DNA repair mechanisms. In their introduction, they had a rather shocking back-of-the-envelope calculation, something like:
(DNA replication errors / cell division) * (cell divisions/day) * (probability of mutation in a cancer related gene) = OH MY GOD WE’RE ALL FULL OF CANCER.
Obviously though, evolution has managed to come up with a multitude of large, long-lived animals that necessarily don’t get much cancer until after their reproductive peak. There are many interlocking layers that control cell division, so a single mutation is almost never enough to cause cancer.
The hard part is defining what exactly is “cancer”. There’s a lot of genetic abnormality that is on the road to “cancer” as we laymen understand it. See Neoplasm - Wikipedia for more.
The concept of what even counts as a cancer has also become more murky, as we now realize that some nodules that look like cancer under the microscope may have no impact on patients’ lives. This Wikipedia quote mentions thyroid and prostate cancer specifically, but the same is true in breast cancer, and probably all over the body. Unfortunately, we are not good at prospectively telling which cancer is a “bad one” and which is “okay”.
I suppose that’s vaguely, misleadingly true, just as you could say that the average person fights off dozens of infections every minute!
In the sense that many times each minute the human body is exposed to a possibly-infectious germ, but the bodies defense mechanisms overwhelm it and dispose of it. That’s their job, and a normal part of their functioning. But this phrasing makes it sound like it is something extraordinary. Just like that statement about cancer. A rhetorical trick, basically.
I can’t find a cite now, but I once read that the average person gets cancer 6-8 times in his lifetime–but most of the time, the immune system takes care of it.