The 10 best supplements for cancer?

Cancer patients are bombarded with information about supplements which allegedly are effective for their condition. I estimate that 99.99% of this information is unreliable and much of it is outright dangerous. So, there is an urgent need for trustworthy, objective information. But which source can we trust?

The authors of a recent article in ‘INTEGRATIVE CANCER THARAPIES’ (the first journal to spearhead and focus on a new and growing movement in cancer treatment. The journal emphasizes scientific understanding of alternative medicine and traditional medicine therapies, and their responsible integration with conventional health care. Integrative care includes therapeutic interventions in diet, lifestyle, exercise, stress care, and nutritional supplements, as well as experimental vaccines, chrono-chemotherapy, and other advanced treatments) review the issue of dietary supplements in the treatment of cancer patients. They claim that the optimal approach is to discuss both the facts and the uncertainty with the patient, in order to reach a mutually informed decision. This sounds promising, and we might thus trust them to deliver something reliable.

In order to enable doctors and other health care professionals to have such discussion, the authors then report on the work of the ‘Clinical Practice Committee’ of ‘The Society of Integrative Oncology’. This panel undertook the challenge of providing basic information to physicians who wish to discuss these issues with their patients. A list of supplements that have the best suggestions of benefit was constructed by “leading researchers and clinicians“ who have experience in using these supplements:

1. curcumin,
2. glutamine,
3. vitamin D,
4. maitake mushrooms,
5. fish oil,
6. green tea,
7. milk thistle,
8. astragalus,
9. melatonin,
10. probiotics.

The authors claim that their review includes basic information on each supplement, such as evidence on effectiveness and clinical trials, adverse effects, and interactions with medications. The information was constructed to provide an up-to-date base of knowledge, so that physicians and other health care providers would be aware of the supplements and be able to discuss realistic expectations and potential benefits and risks (my emphasis).

At first glance, this task looks ambitious but laudable; however, after studying the paper in some detail, I must admit that I have considerable problems taking it seriously – and here is why.

The first question I ask myself when reading the abstract is: Who are these “leading researchers and clinicians”? Surely such a consensus exercise crucially depends on who is being consulted. The article itself does not reveal who these experts are, merely that they are all members of the ‘Society of Integrative Oncology’. A little research reveals this organisation to be devoted to integrating all sorts of alternative therapies into cancer care. If we assume that the experts are identical with the authors of the review; one should point out that most of them are proponents of alternative medicine. This lack of critical input seems more than a little disconcerting.

My next questions are: How did they identify the 10 supplements and how did they evaluate the evidence for or against them? The article informs us that a 5-step procedure was employed:

1. Each clinician in this project was requested to construct a list of supplements that they tend to use frequently in their practice.

2. An initial list of close to 25 supplements was constructed. This list included supplements that have suggestions of some possible benefit and likely to carry minimal risk in cancer care.

3. From that long list, the group agreed on the 10 leading supplements that have the best suggestions of benefit.

4. Each participant selected 1 to 2 supplements that they have interest and experience in their use and wrote a manuscript related to the selected supplement in a uniformed and agreed format. The agreed format was constructed to provide a base of knowledge, so physicians and other health care providers would be able to discuss realistic expectations and potential benefits and risks with patients and families that seek that kind of information.

5. The revised document was circulated among participants for revisions and comments.

This method might look fine to proponents of alternative medicine, but from a scientific point of view, it is seriously wanting. Essentially, they asked those experts who are in favour of a given supplement to write a report to justify his/her preference. This method is not just open bias, it formally invites bias.

Predictably then, the reviews of the 10 chosen supplements are woefully inadequate. These is no evidence of a systematic approach; the cited evidence is demonstrably cherry-picked; there is a complete lack of critical analysis; for several supplements, clinical data are virtually absent without the authors finding this embarrassing void a reason for concern; dosage recommendations are often vague and naïve, to say the least (for instance, for milk thistle: 200 to 400 mg per day – without indication of what the named weight range refers to, the fresh plant, dried powder, extract…?); safety data are incomplete and nobody seems to mind that supplements are not subject to systematic post-marketing surveillance; the text is full of naïve thinking and contradictions (e.g.”There are no reported side effects of the mushroom extracts or the Maitake D-fraction. As Maitake may lower blood sugar, it should be used with caution in patients with diabetes“); evidence suggesting that a given supplement might reduce the risk of cancer is presented as though this means it is an effective treatment for an existing cancer; cancer is usually treated as though it is one disease entity without any differentiation of different cancer types.

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. But I do wonder, isn’t being in favour of integrating half-baked nonsense into cancer care and being selected for one’s favourable attitude towards certain supplements already a conflict of interest?

In any case, the review is in my view not of sufficient rigor to form the basis for well-informed discussions with patients. The authors of the review cite a guideline by the ‘Society of Integrative Oncology’ for the use of supplements in cancer care which states: For cancer patients who wish to use nutritional supplements, including botanicals for purported antitumor effects, it is recommended that they consult a trained professional. During the consultation, the professional should provide support, discuss realistic expectations, and explore potential benefits and risks. It is recommended that use of those agents occur only in the context of clinical trials, recognized nutritional guidelines, clinical evaluation of the risk/benefit ratio based on available evidence, and close monitoring of adverse effects. It seems to me that, with this review, the authors have not adhered to their own guideline.

Criticising the work of others is perhaps not very difficult, however, doing a better job usually is. So, can I offer anything that is better than the above criticised review? The answer is YES. Our initiative ‘CAM cancer’ provides up-to-date, concise and evidence-based systematic reviews of many supplements and other alternative treatments that cancer patients are likely to hear about. Their conclusions are not nearly as uncritically positive as those of the article in ‘INTEGRATIVE CANCER THERAPIES’.

I happen to believe that it is important for cancer patients to have access to reliable information and that it is unethical to mislead them with biased accounts about the value of any treatment.