Why/how does radiation therapy not just cause more cancer?



Isn’t radiation a known way to damage cells and increase the potential for cancer?

In: Biology

Radiation therapy disproportionately damages cells in the process of dividing. Since cancer cells are basically always dividing, this makes them more vulnerable. Additionally, the radiation is targeted so as to attempt to only hit the tumor without damaging nearby tissues.

It does, but with cancer or bad mutations, the cells usually have a self destruct trigger. If the cell has too much DNA damage, it will kill itself. This works 99% of the time, the exception of course is if the self destruct mechanism is damaged.. then you get cancer, cancer.

So when you irradiate, you’re kind of hoping the cells do what they’re supposed to for that 99% of the time, and sometimes it does cause more cancer, rarely happens but yea.

You can think of a cell’s DNA like software. A small amount of damage can lead to bugs. Our cells are fitted out with tools to manage and repair bugs, and other tools that will cause the whole program to just shut down if the bugs are too critical or extensive.

Cancer happens when you get a very specific set of bugs, in very specific order. Starting with the cell’s bug-detection toolkit.

The kinds of DNA damage we encounter in our day-to-day life (for example UV damage) generally don’t cause major damage to the software. Instead, they cause slight occasional changes, spread throughout the code, which can lead to bugs.

Radiation therapy, on the other hand, is targeted, heavy DNA damage. It doesn’t cause small errors throughout the program. It straight up scrambles the software so it won’t even start.

the radiation is focused on the cancer cells, so damaging them is a good thing, and you can’t make them any more cancerous than they already are.

It can, however the cancer one has is much more of a danger than the chance of a new cancer. And chemo drugs have a higher chance of giving one a secondary cancer than the radiation does.

Cell DNA is continually being damaged and repaired. Cancer happens when the repair mechanism breaks.

Granted, focused radiation does an abnormally high amount of damage to DNA in a short period of time. This is mitigated by two factors. 1) Healthy cells can repair. 2) cancer cells are hit by multiple radiation beams at once, but healthy cells are not. Imagine stabbing the tumor with four spears. All the healthy cells on the sides get hit by one spear. So we can figure out how much radiation a healthy cells can tolerate and then use multiple brands to make it deadly at the tumor.

Granted, you raise an excellent point, one potential side effect would be making new cancer cells.