Question: what causes cancer?

Grace Kago answered on 2 Jun 2019:

cancer is a complicated disease that is caused by many reasons including viruses, exposure to toxins, old age, genetic disorders, etc.
At the molecular level, cancer occurs when there are problems with certain regulators in the cells that tell them when to grow, when to stop growing etc. Imagine these regulators to be like that policeman who stands in the road to tell traffic when to stop and go. If this policeman is not there, then cars just go anywhere and there might be chaos and accidents, right?
In the same way, when the proteins that are responsible for telling cells “grow”, “stop growing” are not working, the cells grow too much and overcrowd the normal cells, and then the body cannot function well.