The placebo effect works for almost any condition, except for cancer. Don’t get me wrong, placebos can help combat the symptoms of cancer, but they are useless when it comes to fighting the cancer itself. But why is this?

What is cancer?

Cancer is caused when cells divide uncontrollably. Sometimes these cells form visible masses, known as tumours, but not all cancer is visible. There are many causes of cancer, but it is thought to be primarily down to a genetic mutation. Exposure to radiation, toxins and poor lifestyle can increase your chances of these genetic mutations occurring within your cells, but as much as two thirds of cancer cases can be attributed to random genetic mutations, meaning you might just be unlucky.

How is cancer treated?

The first line of defence is the immune system. Some immune cells are able to recognise and attack abnormal cancer cells. Unfortunately, this is often not a strong enough response to overcome the cancer completely and some cancer cells have adapted to protect themselves from the immune system. There is a theory that suggests that cancer cells are continuously developing in healthy people, but that the immune system is able to destroy them before they cause any problems. It is thought that a dysfunction in the immune response to abnormal cells, may play a role in the development of cancer.

When the immune system fails, cancer cells can become out of control. At this point, cancer is commonly treated with chemotherapy and/or radiotherapy. Radiotherapy uses radiation to destroy cancer cells, whereas chemotherapy uses a range of toxic chemicals instead.

So why doesn’t the placebo effect work for cancer?

Now we’ve established the causes of cancer and how to fight it, we can begin to see why the placebo effect does not work on cancer:

  1. The body is unable to defensively alter its own genetics. Therefore, it cannot overcome the genetic mutations that lead to increased risk of cancer.
  2. The body does not contain its own endogenous (internal) cancer-fighting chemicals, such as those used in chemotherapy. If the chemicals aren’t there, the placebo effect can’t put them there.
  3. The body does not produce its own equivalent to radiotherapy.
  4. If the immune system’s defence mechanisms are damaged, the placebo effect may not have any mechanism by which to encourage the body to act upon the cancer cells.

Don’t give up hope

The placebo effect may not be able to combat cancer, but it has been proven to be effective to reduce the side effects of cancer treatment and to alleviate some of the symptoms of cancer, including:

  • Cancer-related fatigue: A study into the effects of open-label placebos (when the patient knows they’re taking a placebo), found a 29% improvement in the severity of fatigue and a 39% improvement in the degree to which fatigue interrupted quality of life.
  • Chemotherapy-related nausea: Nausea and vomiting are common side effects of chemotherapy, therefore many patients will also be given anti-emetics (anti-sickness) medication to help. It is thought that nausea is often a psychosomatic symptom (a symptom initiated or aggravated by a psychological factor i.e. stress, expectation of nausea etc.). Placebos can work very well for psychosomatic symptoms, and therefore, it should not be surprising that they’re also very effective for nausea. A study demonstrates that placebos have been found to be effective at reducing nausea and vomiting in a hospital setting, suggesting that they would also be effective for combating nausea in a cancer patient.

The verdict on the placebo effect and cancer

Despite some claims, there is little evidence suggesting the effectiveness of placebos in treating cancer. However, that doesn’t mean we should write them off completely! Placebos have been found to benefit people suffering from nausea, cancer-related fatigue and a range of other factors (even if the effects are sometimes small), so there may be a place for them in the future. Where that place could be, I don’t know, but I do think it’s something worth thinking about.

An interesting endnote

A chemotherapy study found that 30% of patients receiving placebos, also lost their hair. Placebo effects with negative outcomes are often referred to as ‘nocebo effects’. [Unfortunately, I can’t find the reference for this study at the moment, but I’ll add it here, when I dig it out again.]

Further reading

2 thoughts on “The placebo effect and cancer – Why not?

  1. There are plenty of cases of spontaneous recovery in cancer patients, so the immune system must be finding a way to overcome the cancer. Perhaps there is a role for placebos to trigger the immune response but we just haven’t found it yet?

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