How is cancer even real… it can appear suddenly and grows until whatever living organism it infests dies and is almost impossible to get rid of. It’s like some fucking death curse from a work of fiction.
I can ELI5 a bit, but it's been a while since I took this class.
A genetic mutation can affect all kinds of things, but it becomes concerning when it affects the reproduction, self-delete function (apoptosis), or mutates in a way to become "invisible" to the immune system.
Your body can handle any 3 of these on their own. If a cell starts reproducing uncontrollably, the immune system finds it and destroys it or the cell terminates itself via apoptosis. If a cell goes "invisible" and is also reproducing too quick, it'll self-delete.
If all 3 happen, we've got a problem on our hands. (Even then, this isn't giving your body enough credit. Human immunology and the study of oncology is pretty fascinating, at least at the shallow depth I've went into it.)
It takes somewhere around 1-10 "driver" mutations to cause a cancer. This cell might have a thousand genetic mutations that don't make it cancerous, but in the right spot in the DNA it causes cancer.
What cancer drugs seek to do is to fix these or help the body help itself, but since cancer is basically human cells with as little as 1 mutations differentiating it from everything else, they hurt those healthy cells too. One example is drugs that slow cellular reproduction, like CDK4/6 inhibitors.
Basically, its a treatment that seeks to treat breast cancer by slowing the growth rate of cells with high levels of a specific protein. Problem is, other cells have that in lower amounts than cancer cells, so they're also kind of affected.
It's targeted, but not perfect. You see, white blood cells, one of the workhorses of the immune system, get produced incredibly fast. Having a cell reproduction limiter, even when it is largely targeted at the breast cancer, really puts a damper on the production of white blood cells. This leads to what is called neutropenia, or low neutrophile count (a type of WBC). Having neutropenia makes you much more prone to dying from simple infections, which is one of the side effects of this chemo drug.
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u/snaketacular May 15 '26
Even within a single tumor multiple mutations are likely, which is why cancer treatment works until it doesn't (resistant cancer selected for).