What Is Homeopathy? Does It Have a Place in Cancer Treatment?

Homeopathy is among the most popular complementary and alternative medicine methods. Developed approximately 200 years ago by German physician Samuel Hahnemann, it has become one of the methods most often used by cancer patients in Europe and America. Based on “like cures like”, it uses repeatedly diluted homeopathic drugs in patients with symptoms resembling those produced by the drugs in healthy people.

It is thought to activate self-healing. Clinical studies have not produced strong evidence for homeopathy in any health condition. Most positive studies also have methodological shortcomings. Because active ingredients are highly diluted, the method is claimed harmless. Adequately diluted products are indeed harmless apart from rare, nonserious effects such as allergic reactions. However, research identifies marketed products inadequately diluted and containing high active-ingredient levels. This risk makes it difficult to call the method entirely harmless.

What Is Homeopathy?

Homeopathy uses highly diluted plant, animal or mineral ingredients to address bodily disorders as a complementary and alternative method. Developed approximately 200 years ago by German physician Samuel Hahnemann (1755–1843), it spread rapidly in Europe and America. It is now among the 10 alternative methods most used by cancer patients. According to America's 2012 National Health Survey, approximately 5 million adults and 1 million children use homeopathic products annually. Compared with 2002 and 2007 surveys, use increases yearly. Another national survey published in 2016 reported use by %2,1 of American adults in the preceding year.

The term comes from Greek homoios (similar) and pathos (suffering), reflecting “like cures like”. Under this principle, drugs tested in healthy volunteers are used for diseases showing symptoms similar to those the drug produces. This is believed to activate the organism's self-healing ability.

What Is Its History, and How Is It Used?

Some sources state Hippocrates used homeopathy in the 400s BC (M.Ö.). He allegedly treated mania with low-dose mandrake root, whose high doses trigger mania (manic-depressive disorder, a psychiatric condition). However, modern homeopathy was developed approximately 200 years ago by Samuel Hahnemann (1755–1843). Testing quinine on himself in 1789, he observed malaria symptoms. He continued similar experiments on people around him and proposed “like cures like”, citing smallpox vaccination as an example. Later studies showed quinine's mechanism was unrelated to his claim: it treats malaria by killing Plasmodium falciparum. His experiments and observations produced 4 principles still forming homeopathy's basis:

• A drug producing symptoms in a healthy person heals a patient with those symptoms when diluted. (Like cures like.)
• Homeopathic drugs are tested on healthy people before use.
• A single-drug approach is most appropriate.
• The drug is potentized to minimize active ingredient (repeated dilution and shaking). Potentization increases its effect. Hahnemann believed it releases a substance's spiritual power, strengthening effects while removing harm. He described the principles in “The Organon of the Healing Art”, published in 1810.

Homeopathy became particularly popular in the 19. century because mortality was lower in homeopathic hospitals during epidemics. Although eclipsed by modern medicine in the 20. century, it regained popularity in the late 20. and 21. centuries.

Assessment has 4 components: history, analyzing the patient to identify a theme, relating symptoms to themes and choosing a drug accordingly. Patients are evaluated holistically, considering physical, emotional, environmental and health circumstances.

What Do Studies of Its Effects Show?

Many studies examine homeopathy in cancer and other diseases. Most have negative findings, though some report benefits; these generally have methodological shortcomings. The United States Food and Drug Administration (FDA) regulated homeopathic drugs but did not evaluate effectiveness and safety. In February 2010, the United Kingdom Science and Technology Committee reviewed clinical records and expert opinions and reported insufficient evidence of effects beyond placebo. As use increased in developing countries, particularly for malaria, AIDS, tuberculosis, diarrhea and influenza, the World Health Organization (WHO) also warned that homeopathy has no role in treating these five conditions.

In 2012, the Australian Government's National Health and Medical Research Council comprehensively evaluated effectiveness evidence and published a report. It found no reliable evidence supporting any health use and said homeopathy should not be used for chronic, serious or potentially serious conditions. Those still using it were warned not to abandon or disrupt established treatments with proven safety and effectiveness.

A 1997 Lancet meta-analysis of 89 studies found insufficient evidence for effectiveness in any condition. A 2005 Lancet meta-analysis of 105 trials supported the view that effects are placebo-based (an inactive substance appears beneficial because the person believes in it). Another meta-analysis in 2000 similarly found insufficient evidence of superiority over placebo. A meta-analysis evaluating the design of 89 trials found greater methodological shortcomings in positive studies, suggesting benefits might largely reflect inadequate design.

Reviews generally do not recommend homeopathy for any health condition. Many found no superiority over placebo. A 2006 systematic review of 6 cancer trials found insufficient data to support use alone or as supportive care. A review in children and adolescents reached similar conclusions. Another review of physical experiments with homeopathic drugs found inadequate controls or other serious errors in most experiments.

A 2003 trial tested whether Belladonna produced specific symptoms in healthy individuals as claimed. It divided 253 volunteers into 2 groups, giving ultramolecular Belladonna to one and placebo to the other. No significant difference emerged. A 2012 trial involving 431 early-stage breast cancer patients found that homeopathic Cocculine added to standard antiemetics did not help reduce chemotherapy-related nausea and vomiting.

Positive studies also exist, but most have methodological limitations. A 2010 observational study found less fatigue with homeopathy added to conventional treatment. Among 25 breast cancer patients with itching in the irradiated area after surgery, 21 improved. Another trial of 66 postoperative breast cancer patients receiving radiotherapy found benefit for radiation dermatitis. In 83 women cured of breast cancer, a mixture of 3 homeopathic drugs was tested for menopausal symptoms; it did not significantly change hot flushes but somewhat improved general health. A similar study of 53 comparable patients found no significant difference.

A 2004 Journal of Clinical Oncology trial divided 254 postoperative breast cancer patients receiving radiotherapy into 2 groups, giving trolamine to one and homeopathic calendula to the other. Calendula prevented acute dermatitis more effectively. A 2015 trial assessing 373 cancer patients observed improved quality of life with homeopathy added to conventional treatment.

Is Homeopathy Safe?

Homeopathic medicines generally involve plant, animal or mineral ingredients repeatedly diluted in water and alcohol. Although usually diluted below dangerous levels, toxic ingredients have been found in some products. Among arsenic-containing product users, 2 cases developed melanosis (skin darkening from excess pigment in tissues), and 1 developed quadriparesis (weakness in both arms and legs). A study measuring toxic metals and metalloids in Croatian products found most below thresholds but dangerous levels in some. Another reported case linked excessive “Lycopodium similiaplex” use to acute hepatitis.

A WHO report involving 105 countries and 400 experts stated that correctly prepared products are generally safe, but high active-ingredient levels in inadequately diluted products may cause side effects. A 2012 systematic review reported allergic reactions and intoxications. Besides direct effects, homeopathic drugs can indirectly harm patients by causing inadequate use of their main treatments.

What Should Be Done, Then?

Clinical studies have not established strong evidence supporting homeopathy in any health condition. Some benefits have been observed, but most do not exceed placebo, and most superior findings have methodological errors. Properly prepared, highly diluted drugs do not cause important side effects. However, some products sold as homeopathic are inadequately diluted, contain substantial active ingredients and may cause adverse effects. Another major risk is causing patients to abandon or disrupt primary treatment. In light of current evidence, avoiding this treatment is advisable.