I wouldn't just say cancer is about "unregulated cell growth". What it's about is a conflict of interest at the cellular level. Some cells become individually f

I wouldn't just say cancer is about "unregulated cell growth". What it's about is a conflict of interest at the cellular level. Some cells become individually fit at the expense of the highly specialized civilization called an organism. It's not just "growth" (mass effect) that makes them so dangerous, because if it were only that, the cancer would just displace stuff (like a benign tumor which, contrary to the name, can kill you-- especially in the brain, where displacement can be fatal because location/connection matters). In addition to reproduction, cancers steal resources from (and starve) or invade healthy cells and cause organs to fail. The underlying theme isn't just "cell growth". It's about cells that override the body's mechanisms for coupling individual fitness with the body's needs. Much of what makes the disease hard to treat is that cancer cells become increasingly fit (individually speaking) over time, and while systemically damaging the environment (e.g. chemotherapy, radiation) works great if it kills all of them, if it doesn't, it leaves an even more fit subset alive.