It used to be we thought of just apoptosis and necrosis, with apoptosis being a clean and deliberate suicide, while necrosis was a messy and uncontrolled cell death.

While those are still very valid, it's turning out that there are a lot more ways for cells to die.

There's necroptosis which is controlled like apoptosis, but messy like necrosis. There's ferroptosis which is iron-reliant and happens in response to excessive oxidation. There's anoikis, which is very similar to apoptosis but initiated by lack of contact to extracellular matrix. There's NETosis, where a type of immune cell called neutrophils eject their DNA as a sticky net to capture pathogens. There's pyroptosis which is triggered by the inflammasome and strongly stimulates inflammation to combat mainly intracellular pathogens.

There are a few more I've left out, probably a few more I haven't heard of, and then all the ones we might not have discovered/characterized yet.

Apoptosis is a "planned" cell death, where either the body commands the cell to kill itself because it's no longer useful or the cell is mortally wounded and dies a tidy death by suicide for the good of the body.

In contrast, cell necrosis is sudden, "messy" cell death that is not considered apoptosis. It can cause problems for surrounding cells as debris, signaling molecules, and even digestive enzymes get released uncontrolled from the dying cell.

Cancer cells are damaged (usually genetically) in a way that causes them to ignore the body's signals to commit apoptosis, but also to ignore signals to not divide and to stay where they are.

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