As with weeds in a garden, it is a challenge to fully get rid of cancer cells in the body once they arise. They have a relentless need to continuously expand, even when they are significantly cut back by therapy or surgery. Even a few cancer cells can give rise to new colonies that will eventually outgrow their borders and deplete their local resources. They also tend to wander into places where they are not welcome, creating metastatic colonies at distant sites that can be even more difficult to detect and eliminate.
One explanation for why cancer cells can withstand such inhospitable environments and growing conditions is an old adage: What doesn’t kill them makes them stronger.
