Why don’t cancer cells die when they should?

Learn in 30 seconds

The main points of this article:

• The danger is not immortality: some cells survive when they should die.
• Healthy cell: DNA damage / aging → apoptosis signal → membrane blebbing → phagocyte clearance (controlled death).
• Cancer cell: apoptosis signal blocked → survival and proliferation (evasion of death).
• A separate feature: longer division capacity (e.g. telomerase). That is not “never dies under any condition.”
• In suitable patients, surgery can be a cornerstone of a plan that aims to eliminate disease.

What is apoptosis? How does the body clear damaged cells?

In healthy tissue, cells renew constantly. Damaged, aging, or no-longer-needed cells are often removed without major collateral damage. That controlled removal is programmed cell death (apoptosis). Think of the left panel of the schematic: DNA damage or aging cue → an apoptosis signal binds the cell → the membrane blebs → the cell fragments → phagocytes clear the pieces. Analogy: the cell “shuts down” in an orderly way; it does not leave a fire behind. Necrosis is a different kind of death: more abrupt and messy, often linked with inflammation.

Source: Kerr et al., 1972 — classic definition of apoptosis.

Two paths: controlled death vs evasion

The same “die” signal can lead to two outcomes — the schematic’s two panels:

• Healthy cell — Programmed death (apoptosis): signal received → blebbing and fragmentation → phagocyte clearance → controlled cell death.
• Cancer cell — Evasion of death: apoptosis signal blocked (anti-apoptotic pathways / mutations) → the cell survives and proliferates → risk of uncontrolled growth.

The real danger is not a guarantee of immortality; it is surviving when death is due.

Why and how does this system break in cancer cells?

Cancer is not one single break. Changes often accumulate over years: age-related DNA damage, some chemicals and tobacco smoke, and rarely hereditary predisposition. One of those changes is weakening of the self-destruction pathway — apoptosis resistance (evasion of death): the cell listens less to the “die” signal. Do not confuse two ideas. Telomerase protects chromosome ends (telomeres). In many cancer types it can turn back on (often cited ~85–90% in the literature) and help cells divide longer. That is not “never dies under any condition.” Evasion of death and long-term division capacity are different; they can appear together. In some tumors the guardian p53 is disrupted. p53 is linked with stopping growth or steering a cell toward death under DNA damage and stress. A p53 gene mutation and dysfunction of the p53 pathway are not always the same thing; roughly half of cancers show this control path disrupted. Your situation is read from pathology and, when needed, molecular testing.

• Evasion of death — Breakdown of the programmed-death (apoptosis) pathway
• Long-term division capacity — e.g. related to telomerase; not the same as evasion of death

Sources: Hanahan & Weinberg 2000/2011; Hanahan 2022; Levine & Oren 2009.

A simple analogy

Think of the inner lining of the bowel. Those cells renew constantly. Aging, damaged, or finished cells are cleared over time and replaced. That order helps keep the tissue healthy. One way the body clears damaged or unneeded cells is programmed cell death (apoptosis). In some cells that control can break. A cell that should be cleared may resist death signals and keep living. When faults in growth-control systems add on, that can contribute to cancer development.

What does this mean for surgery and treatment?

When cancer has formed, the aim of surgery in suitable patients is to remove the tumor with safe tissue margins and eliminate disease when possible. For some people surgery alone may be enough. For others, based on tumor features and stage, add-on treatments may be offered to reduce the chance of unseen cancer cells remaining. That does not mean surgery failed. Surgery, chemotherapy, and other treatments complement each other when needed. Chemotherapy often hits rapidly dividing cells; cells that stay quiet for a long time (dormant) may sometimes be less affected — that topic is covered separately.

• Talking about add-on therapy does not mean “surgery did not work”; it is a separate plan to reduce risk.
• The right options for you are set by your physician and team.

Cancer treatment aims not only to remove the visible tumor, but also to reduce the chance of recurrence as much as possible.

How does this knowledge show up in medicines?

Some drugs aim to reopen the cell’s self-destruction path or disrupt survival signals. That idea led to medicines that reopen the death pathway in selected blood cancers. Example: BCL-2 (a protein that can help a cell stay alive) and venetoclax, which targets it, used in selected chronic lymphocytic leukemia settings. This drug is not used in every cancer. The same logic does not automatically transfer to solid tumors in organs. Drugs and radiation may aim to trigger cell death or slow growth. Because one tumor can hold different cells, responses vary.

• Venetoclax is not used in every cancer.
• The same approach is not automatic for solid tumors.
• This article is not personal drug advice; suitability belongs to your physician.

Source: Roberts et al., NEJM 2016.

What science knows

Points that are firmly accepted:

• Programmed cell death (apoptosis) is an established concept.
• Evasion of death in cancer is a core accepted theme in the field.
• Telomerase can reactivate in many cancers; that is not an “immortality guarantee.”
• Some drugs that target apoptosis pathways are in clinical use for selected diseases.

Not yet settled (do not overstate)

These claims are overstated or not generalizable to every patient:

• Saying every cancer has the same “immortality key” is overstated.
• Treating lab “immortal cell line” language as destiny for every cell in a patient is overstated.
• Saying dormancy models alone explain every late recurrence is overstated.
• Diet or general products as a “guaranteed apoptosis repair formula” is overstated.