Why doesn't an organism with cancer use apoptosis (programmed cell death) to get rid of the extra cells?
Because the body has lost control of those extra cells.
Cancer is basically a single cell losing control of its cell division mechanisms.
Cell division is controlled by two mechanisms:
- Pushing Mechanisms
- Check Point Mechanisms
Pushing Mechanisms are controlled by the cell or by outside signals. This pushes the cell division process forward, preparing the cell to divide and initiating the division mechanisms.
Check Point Mechanisms serve to halt the Pushing Mechanisms at certain points unless it clears certain conditions. Let it checking the integrity of the DNA, checking the right amount of cellular organelles, etc.
Cancer occurs when one or more mechanisms in Pushing or Check Point mechanisms is out of control. Usually do to a mutation or an alteration in the controlling proteins by a carcinogen. This will make the cell keep pushing forward along the division pathway without any regard to external signals, including apoptosis
Think of it like a moving car, how can you control its movement? By either pressing the gas pedal (Pushing Mechanisms) or pressing the break pedal (Check Point Mechanisms). Cancer occurs when one or both pedals are broken. Either gas continuously flood into the engine, or the break isn't working.
I hope this has answered your good question.