Homeopathy is a form of complementary and alternative medicine (CAM) that is based on the “Law of Similars.” According to homeopathic principles, a substance that causes a disorder can be used to treat the condition if prescribed in a very low dosage. Homeopathic remedies are diluted to potencies that vary from 1:10, 1:100, or 1:50,000. These dilutions are repeated until there is not a single molecule of the substance left in the remedy. Mechanisms of action of homeopathy have been attributed to nanoparticles or to “water memory.” This science has been criticized as being greatly flawed.

Researchers conducted a systematic review in February 2021 of five electronic databases (Embase, Cochrane, PsychInfo, CINAHL, and Medline) to identify clinical trials on the use, effectiveness, and potential harm of homeopathy in cancer patients. To be included in this systematic review, studies had to report on patient-relevant outcomes after the use of guideline-based treatment in adult cancer patients. Treatment could include any intervention but must contain homeopathy. Systematic reviews and randomized, controlled trials, controlled trials, one-armed studies, and retrospective studies that were published in either English or German were included in the analysis. Exclusion criteria included studies on primary prevention, gray literature, other publication types other than primary investigation/report (e.g., comments, letters, abstracts), those involving children aged younger than 18 years, or precancerous conditions if results did not separately report on cancerous conditions.

Risk of bias was assessed using the Scottish Intercollegiate Guidelines Network Checklist for controlled trials (Version 2.0) and the Institute of Health Economics Quality Appraisal Checklist for case series studies.

A total of 18 publications met the inclusion criteria and were included in the systematic review. Of these 18 publications, nine were randomized, controlled trials and two were controlled trials. The other seven were included only for safety and side effects due to severe methodological and reporting quality flaws; these included one uncontrolled, three-armed pilot outcome study, five prospective, single-armed studies, and one single-armed, retrospective study.

There were 2,016 patients initially included in the 18 studies, but 422 dropped out, leaving 1,594 for analysis. The mean age of the study population was 54.5 years. Of these patients, 1,448 had a diagnosis of breast cancer (BC), which will be the focus of this article. Other cancer diagnoses that occurred in 473 patients included lung, gastrointestinal, hematological, head and neck, renal cell, pancreatic, other types of cancer, and sarcoma.

These studies assessed the efficacy of homeopathic therapies to mitigate cancer treatment–induced skin reactions, nausea and vomiting, joint pain (JP)/joint stiffness (JS), oral mucositis, and effect of JP on sleep, as well as time to drain removal following mastectomy, survival, hot flashes/other menopausal symptoms, quality of life/quality of recovery/global health and subjective well-being, and anxiety and depression in cancer patients. Safety, tolerance, and side effects were also addressed.

Among the homeopathic products studied for BC treatment–induced conditions were belladonna 7CH globules and x-ray globules for radiation dermatitis (skin reactions); the complex homeopathic product Cocculine for nausea and vomiting; ruta graveolens 5CH and rhus toxicodendron 9CH for JP/JS and/or influence of JP on sleep in patients receiving aromatase inhibitors; Arnica montana Bellis C30 and Perennis C30 for time to drain removal after mastectomy; homeopathic single remedy, Hyland’s Menopause and BRN-01 for hot flashes and other menopausal symptoms; and homeopathic single remedy and Hyland’s Menopause on quality of life and other holistic measures in BC; holistic measures were also discussed for nonsmall-cell lung (NSLC) and head and neck cancer patients. Anxiety and depression were assessed in BC patients, but information on which products were studied was not provided. Oral mucositis was assessed in head and neck cancer patients, and survival was analyzed in patients with advanced NSLC.

Safety, tolerance, and side effects were assessed for Arnica montana, BRN-01, Bella 7CH globules, x-ray globules, verum single remedy, Hyland’s menopauses, and Lymphomyosot.

Overall, all of the studies contained major flaws including methodological deficits in study design (e.g., problems with descriptions of the study populations/patient characteristics, high drop-out rates, discrepancies in the data reporting, variations in doses and durations of interventions within the same study, poorly conducted or improperly interpreted statistical analyses, and different observed endpoints within the same study).

The study on skin reactions yielded conflicting results and used invalid scores. Studies on JP/JS were unblinded, nonrandomized, lacked important inclusion criteria, had uneven control/intervention groups, had questionable endpoints and datasets, used inconsistent data reporting, and had high dropout rates in the homeopathy group. In the studies on drain removal following mastectomy, there were inconsistent findings, with a lack of statistical significance for the analysis of variance and intention-to-treat samples; lack of reporting of patient baseline characteristic, cancer stage, volume of operated breast, and whether reconstruction was performed; unusable per-protocol data due to inconsistent reporting; high and uneven dropout rates; inclusion of both prophylactic and therapeutic mastectomies; interstudy changes in protocol; and incorrect or transposed numerical values.

Studies that examined the effects of homeopathy on hot flashes and menopausal symptoms found that patients were more unsatisfied with CAM than with the placebo with significant increases in hot flashes in the homeopathy-treated group. There were also a high and uneven number of dropouts, low baseline number of hot flashes as inclusion criteria, and missing data and results.

Studies that looked at quality of life and holistic values were unblinded, lacked a placebo or active control group, erroneously reported on different study subpopulations, used invalid test scores, used multiple imputation models without reporting the quantity of the calculated missing data, had high dropout rates, and reported on selected data only. No benefit of homeopathy was reported for the only study that assessed anxiety and depression in BC patients; this study lacked a quality assessment.

Pharmacists should be aware that the scientific literature does not provide any evidence on the effectiveness of homeopathy in cancer. Patients should be cautioned about using these products and should be advised not to substitute homeopathy for conventional medicine. 

The content contained in this article is for informational purposes only. The content is not intended to be a substitute for professional advice. Reliance on any information provided in this article is solely at your own risk.

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