Melatonin and cancer treatments

Melatonin is a compound that is produced in the body by the pineal gland, and is associated with regulation day/night rhythms (also known as the circadian rhythm). Often described as a hormone, melatonin is also known as a powerful antioxidant and has immune stimulating properties, additionally has been shown to have a range of anti-cancer activities in a wide variety of cancer types. It also has a range of medical uses, including as a treatment for insomnia and seasonal affective disorder. Most importantly, it has very, very low levels of toxicity, and does not appear to have negative interactions with a wide range of drugs. This last point is an important one when considering the use of melatonin by cancer patients.

This is interesting in light of a publication of a major review of clinical studies involving melatonin and cancer treatments. The paper, Melatonin as Adjuvant Cancer Care With and Without Chemotherapy: A Systematic Review and Meta-analysis of Randomized Trials, published in the October 2011 edition of the journal Integrative Cancer Therapies, concludes:

MLT may benefit cancer patients who are also receiving chemotherapy, radiotherapy, supportive therapy, or palliative therapy by improving survival and ameliorating the side effects of chemotherapy.

What the authors of this paper have done is gone back and collected all of the data from a range of clinical trials that compared cancer treatments with and without melatonin use. They systematically excluded trials that did not have direct comparisons between treatments that included melatonin and those that didn’t, that did not randomise patients (i.e. trials that gave each patient an equal chance of being on the melatonin arm or the non-melatonin arm – in this way avoiding biasing the results), and they excluded those trials that did not satisfy a range of other quality criteria. At the end of this process there were 21 clinical trials included, all of them looking at patients with solid tumours. The treatments included standard chemotherapy, radiotherapy and palliative care.

The result of pooling the data from these trials was unambiguous. Improvements were found in the numbers of patients achieving complete response, partial response and stable disease. In trials where melatonin was used with chemotherapy, there was a reduced one-year mortality rate – in other words more patients survived. And it was not just improvements in outcome – melatonin use also reduced side effects, including leucopenia, nausea, vomiting and low-blood pressure.

The authors are clear that these are positive results, but as always they hedge their bets by pointing out that few of the trials they included were ‘blinded randomised controlled trials’. These are the gold standard when it comes to medical trials – it means neither the patients nor the doctors treating them know who is getting the drug being tested and who isn’t. This ensures that the there can be no unconscious biases introduced by the doctors or the patients. Another issue they point to, possibly a more important one, is that many of these trials have been carried out by the same small teams – it’s important in medicine for trials to be repeated by many different groups – again to be sure that the results still apply.

However, these caveats aside, the tone of this paper is very positive. More so since there are now a number of larger on-going trials taking place in different centres across the world. And, as an additional point worth making, there is also a steady stream of papers reporting supporting evidence in the form of test tube and animal results.

We have to be clear here – melatonin did not cure people. But it was successful in improving the outcomes for some patients, and it did reduce side effects too. All this from a substance that costs pennies and has very little in the way of side effects.

Aside from anything else, melatonin can act as a powerful weapon in the cancer patient’s fight against fatigue and insomnia. And not just the patient, it’s useful for families and carers too when they are suffering most stress. It’s easily available, and can be prescribed by the NHS in this country, as well as being commonly available on-line. If you think it would be useful then please discuss this with your doctor – if necessary point them to the paper mentioned above, and there are many others available on PubMed or other online medical database.