Two Concepts Closely Related to Cancer: Necrosis and Apoptosis

Understanding why and how cancer develops has taken modern medicine approximately 200 years, and we are still learning. This process contains countless discovery stories, classifiable under important headings. We will briefly discuss two important topics in both medicine and oncology: necrosis and apoptosis.

Necrosis

It frequently appears in pathology reports, and patients often confuse it with cancer itself. However, necrosis is a concept describing cell death. Associated with disruption of cell membrane integrity, leakage of cellular contents and cell breakdown, it largely results from enzymes’ destructive effects on lethally damaged cells. Leaked contents often cause a local reaction called inflammation, whose purpose is to remove dead cells and initiate subsequent repair.

Apoptosis

Although this term does not appear in pathology reports, we wanted to discuss it because of its close relationship with cancer. In normal cellular processes and certain pathological conditions such as cancer, nuclear DNA may direct breakdown of intracellular proteins, leading to cell death. Membranes of cells undergoing apoptosis (English “apoptosis,” sometimes translated into Turkish as “apopitozis”) remain intact, but the cell and its fragments change to become attractive targets for immune cells called phagocytes. Because dying cells and fragments are quickly removed before their contents can leak, apoptotic cell death does not cause an inflammatory response. In these respects, apoptosis differs from necrosis, where membrane integrity is disrupted, cells are digested, contents leak and inflammation often develops.

Apoptosis in pathological conditions: Genetically altered or irreparably damaged cells apoptosis eliminates them without causing severe inflammation. Tissue damage is thus minimized.

For example, DNA damage: Harmful ultraviolet sunlight, tissue oxygen deficiency (hypoxia) and carcinogens such as cigarettes may damage DNA directly or through free radical production. If repair mechanisms cannot cope, the cell activates apoptosis-initiating mechanisms. Destroying the cell may then be preferable to risking cancer-triggering mutations in damaged DNA. Mild harmful effects may cause apoptosis, but much higher doses of the same agents may result in necrotic cell death or cancer formation.

Apoptosis programmed cell death

Apoptosis eliminates unwanted, irreparably damaged cells with minimal inflammatory reaction. It develops in an orderly manner and is also known as “programmed cell death”.

One aim of many cancer treatment methods (such as radiotherapy and hyperthermia) and chemotherapy drugs is also to initiate apoptosis in cancer cells.

Other concepts frequently heard in pathology reports include dysplasia, metaplasia, atrophy, hyperplasia and hypertrophy; you can learn about them through this link.