eli5: How does radiation both cause and cure cancer? I know it can be targeted, but I still don’t understand how it’s not causing cancer at it’s target? How does chemo work? And how does chemo and radiation work together?

Question

Sorry if the flair is wrong. Biology or chemistry?

In: Biology

Answer 1

Small amounts of radiation can cause changes in DNA that turns off the natural programmed cell death and causes uncontrolled growth as a tumour. Larger doses targeted on a specific area causes so much damage to the cells that they die.

Chemotherapy generally locks into DNA and prevents replication. That has a greater effect on fast reproducing cells like tumours (and hair follicles) than it does on the rest of the body.

Together the radiation kills the tumour and chemo mops up anything left, particularly if mutant cells have moved into other parts of the body.