It’s like someone who comes into your house and eats your food and breaks your stuff and hides your bills. At first it doesn’t have a huge impact but eventually your power is cut off because you haven’t paid your bills, you have no food to eat so you are starving, you can’t properly rest because all your furniture is broken… cancer starts by just consuming the resources in your body, and it becomes overwhelming. It spreads to other areas and does the same thing.

It is so dangerous because your immune system doesn’t recognise it because it’s starts as your own cells. So with the person in your house metaphor, it’s someone dressed up like a family member so you let them in, you don’t throw them out even when you know there is a problem because you assume it’s not them that’s causing the problem.

Advanced cancer treatments function by ‘tagging’ the cancer as an enemy so your immune system fights it. But many treatments just try to kill everything in the radius of the cancer, while trying to limit damage to the rest of your body. So again with the house metaphor - you know the problem is in the corner of one room so you basically try to destroy that area without hurting the rest of the house too much. But there is still damage to the structure of the house that has to be repaired afterwards. This is why cancer treatments are so rough, You basically are killing off your own cells too, just trying to kill the cancer faster so that you can have time to recover.