Alternative Medicine and Cancer

 

 

Herbal Anti-Cancer Agents

Many alternative cancer treatments are herbal: Cat's Claw, Essiac, Artemisinin, Mistletoe, Hoxsey's tonic, various Chinese herbal products, mushroom products, etc.  Some are known to have cancer-killing activity in tissue culture,  but that applies to a very wide range of chemicals and is a poor predictor of usefulness in human cancer treatment.  Activity against cancer in experimental animals can also be misleading,  as shown by recent disappointing performance in humans of angiogenesis inhibitors that had shown great promise in animal studies.

Nevertheless, newer herbal methods cannot be dismissed out of hand.    Plant derivatives have a very strong track record in the mainstream chemotherapy of cancer.  The Vinca alkaloids are made from the periwinkle plant. The taxanes are made from the bark of the Pacific yew tree.   The podophyllotoxins are derived from the Mayapple, and   Camptothecan from the Asian "Happy Tree" .     

Some herbal agents  beg the question of what makes an agent ralternative".   Artemesinin, for example, might more accurately be described as an experimental treatment.   Already in wide use in the treatment of malaria it has shown some promise for cancer in test tube and animal experiments.   It so far lacks convincing evidence of usefulness in human cancer.   Older herbal agents such as Hoxsey's formula and Essiac have to be regarded as almost certainly worthless for internal cancers.    Either preliminary medical investigations have failed to find convincing benefits from them or widespread usage has failed to produce any body of quality anecdotal material (the Hoxsey  "Black Salve", like any other escharotic,  would have an  imprecise destructive effect on very superficial skin cancers). 

New herbal agents pop up all the time, and patients with serious cancer might quite reasonably argue that they cannot wait for their slow, methodical evaluation.   Those marketing such products certainly encourage this attitude in justification of a near-criminal neglect of the simplest research into dose-finding and efficacy.  .    

There are some important matters to consider before using herbal methods.   

Dosage is usually critical in anti-cancer agents,  yet alternative herbal products are routinely found to vary widely in their content of active ingredients.    This is understandable when that can vary enormously within  the native plant, as much as  80 fold  (0.01-0.8 %)  in the case of Artemesinin in Artemisia  Annua   [2].    Patients should buy only from reputable sources, although I am not sure that is decided or how much of a guarantee it is - the "food supplement" industry is barely regulated or monitored.     It should be possible to buy pharmaceutical grade Artemesinin (or its semi-synthetic derivatives), because of other medical uses.

Even with a standardised product,  alternative herbal agents are not likely to be advised in optimal dosages.  As mentioned above,  they will never have been put through the simple Phase l and Phase ll clinical studies (see  Footnote ) needed to work that out.    The reliance on weak patient testimonial, or traditional usage, usually for complaints other than cancer,  merely creates the illusion that effective dosage is known.   

Herbs are also usually assumed to be safe and "natural", yet every one of those promoted as a possible cancer cure including Artemisinin are known to have the potential for serious side effects.  This raises another matter.   

Plants  produce poisonous chemicals almost as a routine.  These only incidentally have uses in medicine   Experience suggests that any new herbal anti-cancer agent will suffer from the same limitations and disadvantages as the herbal agents already in use.   This means that It will work best when used in maximum tolerable dosages [1].     It means that If it is able to cure some kinds of cancer, it will perform best in dosages that risk  significant side effects, and also when combined with other anti-cancer drugs having different modes of action.    It means that the remissions produced will often be temporary  and followed by resistance to further treatment by the same agent.    

With the marketing of alternative methods being so heavily dependent upon the supposed contrast between "safe, natural" methods and chemotherapy and other conventional methods,  it is most unlikely that any alternative cancer-killing agents will be ever be advised  in effective dosage.    They will in consequence almost certainly not  perform as well as conventional chemotherapy might, while still having the potential to produce resistance to further chemotherapy,  through the induction of MRP (multi-drug resistance-associated protein)  pathways, or the selecting out of resistant cells, in the same way that antibiotics can select out antibiotic resistant strains of bacteria.   

Cancer sufferers may thus be wise not to toy with them if conventional chemotherapy  (as opposed to what is essentially ralternative chemotherapy"),  is  likely to be considered at any stage.    

These matters make it difficult for doctors to wholly endorse the use of alternative herbal agents, even when showing potential in laboratory studies..   Cancer patients should certainly not have too high expectations of them as currently supplied.     

It would be infinitely preferable if newer herbal agents were first supplied to cancer patients free of charge as part of proper Phase l and ll studies, as they are in conventional medical research.   We might then learn something useful about them.  Sometimes alternative medicine resembles a vast medical experiment in which no one is looking at the results.      

Herbs are also sometimes claimed to act as immune modulators, and can be shown to have such effects in test tube or animal studies.   The effects of such agents are likely to be more subtle, with the possibility of them either prolonging survival  or increasing the remission/cure rate when used along with other agents.    Such usage might make more sense, if true.   They are sold, however, with absolutely no evidence that they are of benefit to cancer sufferers in practice, and with similar uncertainties as to correct dosage or possible ill effects.      

[1]    See, for example    http://theoncologist.alphamedpress.org/cgi/content/full/3/5/365   

Footnote 

Characteristics of the three phases of US clinical trials.


Phase I   Initial study in humans   Designed to gather data on dosage, timing and safety, but not efficacy.
Involves a small number of patients.   Determines maximum tolerable dose
 

Phase II  Continued evaluation of safety.  Initial evaluation of efficacy.  May be larger number of patients
 

Phase III  Large-scale study to assess efficacy, with continued evaluations of safety.  Designed to determine if the new treatment is better than the current standard of care