There's no convincing evidence to show that homeopathy relieves treatment side effects

There's no convincing evidence to show that homeopathy relieves treatment side effects

Treating cancer can be gruelling, and patients often suffer side effects as a result of modern treatments. This is because it is very difficult to accurately target drugs or radiotherapy specifically to cancer cells. And because these treatments have powerful biological effects on cells, there is an inherent risk that healthy cells may also be damaged, causing side effects.

This week saw the publication of a comprehensive review of clinical trials investigating whether homeopathy can help with the side effects of cancer.

The review showed that homeopathic treatments did not interfere with cancer therapy. But with the exception of two specific treatments (at least one of which, it could be argued, is not truly homeopathic), there was no convincing evidence that homeopathy helped with the side effects.

However, some headlines gave a different impression – for example “Homeopathy ‘eases cancer therapy’” or “Homeopathy appears compatible with cancer therapy”.

Let’s take a closer look at the story to find out what’s really going on.

What is homeopathy?
Homeopathy is a form of alternative or complementary medicine that was first developed back in the 18th century.

The most commonly understood idea behind it is that the patient is treated with extremely diluted solutions of substances that would cause effects on the body similar to the symptoms of the disease. Usually, these solutions are so dilute that there are effectively no molecules of the original substance left in the water.

It’s a quaint idea, but there is no plausible scientific explanation as to how homeopathy might actually have a biological effect on the body. There are plenty of stories from people who have used it to find relief from various conditions, but there is no scientifically robust evidence to show that homeopathy works any better than a placebo (dummy treatment).

And, as you might expect, the most commonly held explanation for how homeopathy works is through the placebo effect.

Who did the review?
The new review comes from the highly respected Cochrane Collaboration. This is an international non-profit organisation producing expert reviews of scientific evidence for the benefits (or not) of medical treatment, from heart disease to cancer to tooth decay, and everything in between.

They scrutinise conventional medical treatments alongside alternative and complementary therapies, aiming to provide doctors worldwide with the latest information about the most effective treatments.

In this review, experts (who were from the field of homeopathy and complementary medicine) pulled together the results of as many randomised controlled clinical trials as they could find where homeopathy had been tested for the relief of cancer treatment side effects. The experts did not include trials that did not stand up to scientific scrutiny – for example, they were biased, or did not include controls.

In total, they found just eight suitable trials – seven comparing homeopathy with a placebo, and one testing it against an active (i.e. medical) treatment – with a total of 664 patients. Three trials looked at the side effects of radiotherapy, three looked at the side effects of chemotherapy, and two studied menopausal symptoms (such as hot flushes) that can be brought on by certain breast cancer treatments.

What did they find?
Out of the eight trials, just two gave positive results for homeopathy that were unlikely to be the result of bias or flawed methods. In the highest quality study, scientists found that an ointment containing an extract of calendula, a type of marigold, could prevent skin irritation caused by radiotherapy in a trial of 254 patients. The trial showed that it was more effective than the conventional cream, called trolamine.

It is important to point out that it is doubtful whether the calendula ointment is a typical homeopathic treatment, as it is not highly diluted. Remember that homeopathic remedies are almost always just water – they effectively contain none of the original substance. So the calendula ointment is more like a herbal treatment, which may well contain biologically active chemicals.

And the trial wasn’t blinded, as there was a significant difference in the smell, colour and texture of the calendula treatment compared with trolamine. In blind trials, neither the patients nor the researchers know which treatment someone is getting. This avoids biasing the results, whether intentionally or not.

In another study of only 32 patients, researchers found that a dilute herbal mouthwash called Traumeel S was more effective at relieving mouth inflammation (stomatitis) in children undergoing bone marrow transplants for cancer, compared with a salt water mouthwash.

Although this study was blinded, and there was no difference in taste or colour between the two treatments, this study was very small. According to the Cochrane review, researchers are currently repeating the study to see if the results are the same, and also testing Traumeel S in a patients receiving radiotherapy for head and neck cancers.

What next?
Perhaps the most striking – and underplayed – conclusion of the review is that there is a severe lack of high-quality studies into homeopathy. Given that conventional medicine seems to have no problem designing scientifically rigorous clinical trials that demonstrate whether a particular treatment works or not, it is notable that so few have been done for homeopathy.

It is not for lack of money. Homeopathy is big business, particularly in countries like Germany. Yet there is a distinct lack of scientific evidence that the treatment actually works in its own right, as opposed to merely being a placebo. Nor is it for a lack of time. Homeopathy has been around for centuries, and yet there is still no strong scientific evidence that it works.

It is also disappointing that many of the news reports have gone for the angle that homeopathic treatments do not interfere with conventional cancer therapy. Surely the important part of the story is that the treatments don’t work, not that ineffective, highly diluted treatments (unsurprisingly) don’t interfere with chemotherapy or radiotherapy.

This is not a dismissal of all complementary therapies for relieving the side effects of cancer treatment. There are a few areas where scientifically solid studies have shown benefits for patients.

For example, we’ve previously blogged about a Cancer Research UK-funded study of aromatherapy massage for relieving anxiety and depression in people with cancer. And we are also currently funding a trial to find out if acupuncture can help to relieve severe mouth dryness caused by radiotherapy for head and neck cancers.

The important thing to note is that these treatments are prepared to stand up to scrutiny in rigorously-designed clinical trials. And there is significant evidence that they may bring benefits to patients – otherwise we wouldn’t be funding them.

In the case of homeopathy – as understood to mean treatment with extremely diluted solutions – there is simply no evidence that it works, either to treat disease or to relieve the side effects of conventional cancer medicine. And the scientific explanation behind the therapy is deeply flawed.

Scientists and doctors have put a lot of effort into developing ways to reduce the side effects of cancer treatment. For example, we recently opened our new Radiation Oncology and Biology Institute in Oxford, where researchers are developing ways to target radiotherapy more precisely to tumours.

Our drug development programmes are focusing on “smart” drugs that target the faulty molecules and biological pathways within cancers, steering clear of healthy cells. And increasingly scientists are investigating how an individual’s genetic makeup affects the effectiveness of their treatment, allowing it to be tailored more precisely, reducing side effects.

We acknowledge that it is important to consider the side effects of conventional cancer treatment, and work towards relieving or removing them as far as possible. But the only effective way to do this is through therapies that have been proven to work. And, as this review shows, this isn’t the case for homeopathy.


PS This story has been covered on a number of science blogs, including Quackometer and Neurologica.

The pdf version of the review is available online.


Kassab S, et al. (2009). Homeopathic medicines for adverse effects of cancer treatments. Cochrane Database Syst Rev. , CD004845

Pommier, P. et al (2004). Phase III Randomized Trial of Calendula Officinalis Compared With Trolamine for the Prevention of Acute Dermatitis During Irradiation for Breast Cancer Journal of Clinical Oncology, 22 (8), 1447-1453 DOI: 10.1200/JCO.2004.07.063

Oberbaum, M. et al. (2001). A randomized, controlled clinical trial of the homeopathic medication TRAUMEEL s� in the treatment of chemotherapy-induced stomatitis in children undergoing stem cell transplantation Cancer, 92 (3), 684-690 DOI: 10.1002/1097-0142(20010801)92:33.0.CO;2-#