eMJA: Ernst, A primer of complementary and alternative medicine commonly used by cancer patients

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A primer of complementary and alternative medicine commonly used by cancer patients

Edzard Ernst

MJA 2001; 174: 88-92

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Abstract - Acupuncture - Diets - Aromatherapy - Chiropractic - Coffee enemas - Herbal medicinal products - Homoeopathy - Meditation - Ozone therapy - Shark cartilage - Spiritual healing - Comment - References - Author's details
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Abstract

Complementary and alternative medicine (CAM) is frequently used by cancer patients, and many oncologists have limited knowledge of CAM.
This article provides a brief, evidence-based introduction to several CAM treatments relevant in the context of cancer.
"Alternative" diets, chiropractic, coffee enemas, ozone therapy, and shark cartilage seem to have little to offer cancer patients.
The evidence for or against homoeopathy and spiritual healing is at present inconclusive.
Acupuncture, aromatherapy, and meditation may be useful for nausea/vomiting, for mild relaxation, and for pain/anxiety, respectively.
Herbal treatments offer no reasonable prospect of a cure (mistletoe), but could be useful as palliative treatments (eg, for depression [St John's wort] or anxiety [kava]).
Our knowledge regarding the potential benefit and harm of CAM is insufficient.

The prevalence of use of complementary and alternative medicine (CAM) for treating cancer is high: a systematic review of all surveys published by 1998 indicated an average prevalence of 34%,¹ a figure which is close to that observed for Australia,² but markedly lower than the 75% reported recently in the United States.³ Cancer patients generally report satisfaction with CAM^1,2 and rarely inform their doctors about their CAM use.⁴ Consequently, many oncologists have limited knowledge of the subject.⁵

My aim is to provide a brief introduction to those CAM modalities which have been identified as most relevant:^1-5 acupuncture, "alternative" cancer diets, aromatherapy, chiropractic, coffee enemas, herbal medicinal products (HMPs), homoeopathy, meditation, ozone therapy, shark cartilage, and spiritual healing. Particular emphasis is placed on reliable evidence (eg, randomised clinical trials, or systematic reviews and meta-analyses of such studies) regarding safety and effectiveness. It is important to note that this article is not a systematic review of all available data.

Acupuncture

Acupuncture constitutes one of several elements of Traditional Chinese Medicine (TCM). Advocates of TCM view ill health as an imbalance of the life force "Qi", which is believed to flow in channels called meridians. To restore the balance (and thus health), the flow of Qi can be influenced by stimulating acupuncture points located along meridians. Typically, this is done by inserting needles, but heat (moxibustion), external pressure (acupressure), electrical currents (electroacupuncture), laser (laser acupuncture), and other stimuli are also used.⁶ Acupuncture is one of the best-known forms of CAM.⁷

Several hundred controlled clinical trials of acupuncture for a range of conditions have been published (for a review, see ref. 6). Such trials face formidable methodological challenges (eg, blinding or controlling for placebo effects), an issue that also applies to many other CAM treatments. Often the results of individual studies are contradictory. Thus, systematic reviews (including meta-analyses) of the totality of the trial data present the least-biased assessment.

Box 1 provides an overview of the conclusions from all systematic reviews and meta-analyses of acupuncture currently available.⁶ There is good evidence for the use of acupuncture for non-specific back pain, dental pain, migraine, and nausea/vomiting. Of these conditions, only nausea and vomiting are directly relevant to cancer patients. There are many conditions for which substantial uncertainty remains (in spite of the availability of clinical trials) (Box 1), and future trials are required to define the effectiveness of acupuncture in these situations.

Serious risks of acupuncture pertain mainly to tissue trauma (eg, pneumothorax) and infections (eg, hepatitis). They are usually avoidable and extremely rare.⁸ Less serious adverse effects (eg, pain of needle insertion or minor bleeding at the site of insertion) are much more common but transient.⁹

"Alternative" cancer diets

More than 40 different cancer diets have been claimed to prevent and/or treat cancer.¹⁰ Several of these diets are an extension of conventional medicine, whereas others are considered more in the realm of CAM. The diets typically emphasise avoiding meat, and many are strictly vegetarian. Compelling evidence is largely absent.

Two diets deserve particular mention. The Gerson diet is basically a vegan form of nutrition. Patients consume the juices of about 9 kg of fruit and vegetables per day (primarily carrots and apples). The diet is often supplemented with coffee enemas. The "Gerson Institute" offers anecdotal evidence of success in its promotional literature, and a retrospective analysis¹¹ of 153 melanoma patients suggested an impressive prolongation of the five-year survival rates of Gerson patients compared with patients in orthodox care. This study was retrospective, its sample size was small, and about a third of all patients were lost to follow-up. Bias was further introduced by use of a self-selected sample, and through the use of non-randomised controls.

The Macrobiotic diet is based on the belief that cancer is caused by an imbalance of yin and yang. It is assumed that imbalances can be corrected by eating foods with either yin or yang qualities. The Macrobiotic diet is composed primarily of whole-grain products (50%-60%) and fresh vegetables (20%-40%). Meat and milk are not allowed, but small amounts of fish are permitted. Macrobiotic diets allow few fluids but they require large amounts of salt intake (about 30 g/day). There is no clinical evidence to suggest that this diet prevents, alleviates or cures cancer.¹²

There are positive aspects to some cancer diets (eg, a reduction in red meat consumption, increase in intake of fruit, vegetables and fibre). However, dogmatic adherence to an unbalanced diet is clearly counterproductive and some CAM cancer diets (eg, Gerson, Macrobiotic, strict vegan) carry the risk of malnutrition.

Aromatherapy

Aromatherapy is the medicinal use of concentrated volatile oils extracted from plants.¹³ The term was first used in 1936 by the French chemist Gattefossé.¹⁴ Today it usually implies gentle massage therapy with a range of aromatic plant extracts known as essential (ie, volatile) oils.¹⁵

A recent systematic review summarised all randomised controlled trials (RCTs) testing the clinical effectiveness of aromatherapy.¹⁶ Twelve trials were found; six of them had no independent replication and six related to the relaxing effects of aromatic oils applied through gentle massage. These studies suggest that aromatherapy massage has mild and transient anxiolytic activity. Even though the effects are likely to be small, they may have benefits for cancer patients in terms of enhancing feelings of wellbeing.

There are few risks associated with aromatherapy. Although some oils are potentially carcinogenic,¹⁷ the exposure rate for patients (but perhaps not for therapists) is probably too low to constitute a real danger.

Chiropractic

Chiropractic is "a system of health care founded in 1895 by Daniel David Palmer which is based on the belief that the nervous system is the most important determinant of a person's state of health; according to chiropractic theory, most diseases are the result of 'nerve interference', caused by spinal subluxations, which respond to spinal manipulation".¹³ Chiropractors employ spinal manipulation (eg, high-velocity thrusts), mobilisation (eg, low-velocity techniques), and other forms of natural medicine.

A systematic review of conservative treatments for neck pain/headache failed to show convincingly that chiropractic is more effective than other interventions.¹⁸ A meta-analysis of chiropractic for low back pain published in 1992¹⁹ suggested that chiropractic is effective for acute low back pain. For chronic low back pain, the evidence was less convincing. A more recent and more rigorous systematic review concluded that "the available randomised clinical trials provided no convincing evidence of the effectiveness of chiropractic for acute or chronic low back pain".²⁰

Owing to lack of data, no firm conclusions are possible for the effectiveness of chiropractic for other conditions. One exception is asthma, where two rigorous, sham-controlled RCTs showed that chiropractic is no more effective than sham interventions.^21,22 There is no evidence that chiropractic alleviates symptoms related specifically to cancer.

About 50% of patients treated by chiropractors will experience mild and transient adverse effects, mostly local or distant pain lasting for one or two days.^23,24 Serious complications of chiropractic are probably rare events that occur predominantly after manipulation of the cervical spine. A recent review described 32 fatalities associated with upper spinal manipulation.²⁵ In addition, significant indirect risks are on record. Examples are the overuse of x-rays by some chiropractors²⁶ and their tendency to advise against vaccination.²⁷

Coffee enemas

Coffee enemas are a derivative of colon therapy (ie, water enemas).²⁸ As part of the Gerson diet,¹¹ coffee enemas are usually administered on a four-hourly basis "to help relieve pain, nausea and other symptoms accompanying detoxification".²⁹ Proponents claim that caffeine is absorbed in the colon, leading to vasodilatation of the liver, which in turn enhances the process of elimination of "toxins".²⁹ These assumptions are unproven. There is no reliable evidence of the clinical efficacy of coffee enemas for any indication.

Coffee enemas are regularly associated with adverse reactions (eg, electrolyte imbalances), some of which are severe.³⁰ On balance, therefore, no reasons exist for recommending coffee enemas to cancer patients.

Herbal medicinal products

With many medicinal plants, it is not possible to define the principal active constituents; the clinical effects of most HMPs are produced by more than one active compound, and in many instances the full range has not been identified. Thus, the conventional pharmacological wisdom of isolation and synthesis of (single) active ingredients is often not a viable option.

Several traditions of herbal medicine (eg, Traditional Chinese Medicine, Ayurveda) typically use complex, often individualised, mixtures of several (sometimes more than 20) medicinal herbs in one single prescription. However, most modern self-prescribed HMPs consist of one single herb. Several such HMPs have been submitted to relatively extensive clinical tests. Box 2 provides an overview of HMPs for which sufficient trial data as well as systematic reviews or meta-analyses exist (for a review, see ref. 31). It is obvious that each HMP (for each indication) has to be evaluated on its own merit -- generalisations regarding the efficacy (and safety) of HMPs are nonsensical.

For other HMPs, efficacy remains uncertain. Mistletoe (Viscum album) is often recommended as a treatment for cancer. It gained widespread popularity in Europe, which now also extends to the US and Australia. Its proponents claim that it arrests or delays tumour progression and improves quality of life. Mistletoe lectins have been shown repeatedly to exhibit antineoplastic activity.³² However, a systematic review of all 11 controlled clinical trials yielded disappointing results.³³ The average methodological quality of the primary studies was poor. The results of most trials favoured mistletoe, but the most rigorous study did not demonstrate efficacy. The authors therefore concluded that they "cannot recommend the use of mistletoe extracts in the treatment of cancer patients with an exception for patients involved in clinical trials".³³ Since the publication of that report, several new studies have emerged, but the overall conclusion has not become more positive.³⁴

Homoeopathy

Homoeopathy is based on two highly controversial principles: the law of "similars" (ie, like cures like), and the notion that highly "potentised" (diluted) remedies can be effective, even though they are unlikely to contain a single molecule of the original substance. Scientists insist that where there is no molecule there can be no effect; all clinical effects of homoeopathy, they maintain, must therefore be due to placebo.

A meta-analysis of all 123 randomised or placebo-controlled trials concluded that the clinical effects of homoeopathy are not entirely due to placebo.³⁵ This meta-analysis has been criticised for pooling data relating to all types of indications and remedies. It may therefore be relevant to assess defined indications and remedies and see what evidence for or against homoeopathy emerges. The remedy that has been submitted to more controlled clinical trials than any other homoeopathic medicine is Arnica montana (a plant-based homoeopathic remedy often used for alleviating bruising and other tissue trauma). Two independent systematic reviews of all studies of homoeopathic arnica provided no conclusive evidence that it is clinically more effective than placebo.^36,37 The condition most frequently employed for testing the efficacy of homoeopathic remedies is delayed-onset muscle soreness. A systematic review of all relevant trials produced no convincing evidence that homoeopathic remedies are superior to placebo in treating this condition.³⁸ In their daily routine, homoeopaths are more likely to aim at alleviating ailments like asthma or headaches; systematic reviews found no good evidence to suggest that homoeopathic remedies are efficacious for either of these conditions.^39,40 Most homoeopaths would claim that their approach can alleviate symptoms associated with cancer and therefore has a role in supportive/palliative care. Reliable evidence to substantiate this claim is lacking.

Highly diluted homoeopathic drugs are obviously devoid of adverse effects, but low dilutions may cause adverse effects (eg, allergic reactions). Homoeopaths claim that, in about 20% of all patients, they would see an acute clinical deterioration ("homoeopathic aggravation") if the optimal remedy has been administered. Such aggravations might constitute a safety issue in their own right. Finally, some non-medically qualified homoeopaths advise their clients against vaccination,³⁷ which clearly constitutes an indirect risk of homoeopathy.

Meditation

Meditation is a general term describing treatments in which a person empties his/her mind of extraneous thought with the intent of elevating the mind to a different level and transcending mundane concerns.¹³ A wide array of techniques exist which fall into two broad categories: emphasis on concentration (eg, Transcendental Meditation) and emphasis on mindfulness (eg, Vipassana). The techniques can be learned from experienced teachers during a series of tutored sessions.

The physiological effects of meditation are those of deep relaxation. A typical relaxation response includes the cardiovascular (eg, decrease in blood pressure and heart rate) and the endocrine (eg, decrease in stress hormones) systems. There is evidence from controlled clinical trials suggesting that these effects can be used clinically to control cardiovascular risk factors, chronic pain and anxiety,⁴¹ which could be of benefit to cancer patients.

Potential adverse effects of meditation include psychological symptoms such as tension, anxiety, depression, and confusion. A syndrome termed "meditation sickness" has been recognised.¹³ Meditation is contraindicated in patients with psychotic or borderline personality disorders.⁴¹

Ozone therapy

Several techniques of administering ozone are being promoted as a treatment for cancer.⁴² The "optimal" system is apparently via the exposure ex vivo of up to 300 mL of freshly drawn blood to a gas mixture of oxygen and ozone, followed by reinfusion of this blood into the patient.⁴³ Numerous mechanisms of action are quoted in support of ozone therapy. However, few rigorous clinical trials of the treatment exist. Those that have been published demonstrated no evidence of effect.^44,45

The risks of ozone therapy are played down by its proponents.^42,43 Yet, numerous reports of serious complications, including hepatitis, and at least five fatalities have been reported.^46,47 Until more positive evidence emerges, ozone therapy should be avoided.

Shark cartilage

Shark cartilage is perhaps the most widely promoted CAM "cancer cure" in recent years. In 1995, the annual world market for shark cartilage products exceeded US$30 million.⁴⁸ Two glycoproteins (sphyrnastatin 1 and 2) have been isolated from the cartilage of the hammerhead shark and were reported to have strong antiangiogenic activity inhibiting tumour neovascularisation,⁴⁹ an effect which could be helpful in human cancer therapy. However, as macromolecules are not usually absorbed by the intestinal tract, it is questionable whether the sphyrnastatins ever reach the bloodstream in sufficiently high concentrations.

To date, no controlled clinical studies testing the efficacy of shark cartilage have been published. Preliminary results have been reported from a US trial: 50% of cancer patients who took 100 mg dried cartilage powder daily reported improvements in quality of life, appetite and relief of pain.⁵⁰ More recently, a well-documented trial was published.⁵¹ Sixty patients with various advanced cancers received 1 g/kg shark cartilage daily for 12 weeks. No complete or partial responses were noted, and the authors conclude that "shark cartilage as a single agent was inactive in patients with advanced-stage cancer and had no salutary effect on quality of life".⁵¹

Spiritual healing

Spiritual healing has been defined as the direct interaction between one individual (the healer) and a patient, with the intention of improving the patient's condition or curing the illness.⁵² Treatment can occur through personal contact or at a (sometimes large) distance. Several variations exist (eg, therapeutic touch, Reiki, faith healing, intercessory prayer), and therapists of one group see themselves as distinct from other groups. Spiritual healers, who are usually not medically qualified, believe that the therapeutic effect results from the channelling of "energy" from an undefined source via the healer to the patient; there is no evidence that this energy actually exists. The central claim of healers is that they promote or facilitate self-healing and wellbeing, both of which could be relevant to cancer patients.

The evidence from randomised controlled trials of all distant healing approaches on human patients is highly conflicting. A systematic review of 23 randomised and adequately controlled clinical trials found that about half of these trials suggested that healing is effective (ie, better than control interventions). Yet methodological shortcomings prevented firm conclusions.⁵³

As long as it is not used as an alternative to effective therapies, spiritual healing should be virtually devoid of risks.

Comment

It has to be stressed again that this article is a mere primer and not an in-depth analysis of the existing evidence. CAM includes several hundred treatments. Because of the obvious constraints of space only 11 were discussed briefly. Inevitably, other important treatments (eg, osteopathy, hypnotherapy, naturopathy) had to be omitted.

Much of the above evidence indicates that CAM, even though used frequently by cancer patients, is not supported by compelling data. This is particularly true for CAM as a cancer cure. The role of CAM as a palliative or supportive cancer treatment might be slightly different.⁵⁴ Several CAM modalities have the potential to increase wellbeing with little potential for harm (eg, acupuncture, reflexology). This raises the complex question of what evidence is required for such therapies. Is it enough that individual patients desire CAM and feel better with it, or does one need to demonstrate that the CAM intervention in question is at least as effective and/or cost-effective as conventional palliative care? These questions require serious consideration and further, detailed discussion.

The potential for harm is considerable for several of the CAM treatments (eg, chiropractic, coffee enemas, ozone therapy, HMPs). Ideally, one would want exact incidence figures of adverse events and conduct proper risk-benefit analyses. Unfortunately, for most forms of CAM, such data are not available. Future research should focus not merely on the efficacy but also on the safety of CAM. The ultimate question that needs answering is, does a given CAM intervention do more good than harm to cancer patients?

In conclusion, cancer patients frequently use CAM. For most of these treatments the evidence is woefully incomplete. One challenge for the future is to adequately match CAM's popularity with an evidence base.

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Authors' details

School of Postgraduate Medicine and Health Sciences, University of Exeter, Exeter, UK.

Edzard Ernst, PhD, FRCP(Edin), Professor, Department of Complementary Medicine.

Reprints: Professor E Ernst, Department of Complementary Medicine, School of Postgraduate Medicine and Health Sciences, University of Exeter, 25 Victoria Park Road, Exeter EX2 4NT, UK.
E.ErnstATexeter.ac.uk

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