Advising Patients About Alternative Cancer Treatments

Source: Tufts University
February 14, 2003

People with cancer who are looking for more treatment options often turn to non-traditional alternatives such as herbal supplements, dietary modifications, and acupuncture. But many of these treatments come recommended only by anecdotal support rather than by solid scientific evidence. Researchers from Canada and the United States recently summarized what is known about the efficacy and safety of several popular complementary and alternative medicines (CAM). Their analysis was published in a recent issue of Annals of Internal Medicine.

Data analysis

The scientists identified studies that examined CAMs commonly used by people with cancer. Randomized, controlled trials (RCTs) were given the most credit. If none could be identified for a particular treatment, then uncontrolled and observational findings were evaluated, but were not considered conclusive. The authors evaluated both efficacy and safety of various treatments - macrobiotics diets, vitamins A, C, and E, soy and shark cartilage - and categorized them as to whether they could be 'reasonably recommended', 'accepted', or their use should be 'discouraged' by physicians.

Macrobiotic meals and soy
Proponents of a macrobiotic diet - a very low-fat diet that is based on a limited variety of whole grains, vegetables and fruit - claim that it can cure and prevent diseases, including cancer. But there is no evidence that a macrobiotic diet has healing properties beyond the possible benefits of a diet that is high in fiber and low in fat. The traditional macrobiotic diet is deficient in many key nutrients and is not a good choice for patients already challenged by serious health concerns.

It is still unclear as to whether the isoflavonoid phytoestrogens in soy are beneficial or harmful to those with estrogen-dependent cancers like breast cancer. In vitro data suggest that isoflavonoids may enhance breast cancer cell growth, while others indicate an antitumor effect. Currently, it seems prudent to discourage patients with breast cancer from using soy supplements. These supplements might, however, be beneficial to men who have prostate cancer. (A randomized controlled trial of the effect of isoflavones on prostate cancer is currently underway.)

Vitamin Supplements
The authors advise people being treated for cancer not to take high doses of vitamin A, C, or E. Supplemental doses of vitamins C and E - both potent antioxidants - can interfere with the action of chemotherapy drugs. Two large RCTs suggest that high doses of vitamin A may actually increase lung cancer incidence among high-risk groups.

Also a consideration is that vitamin E can interfere with platelet aggregation, and should be used cautiously by patients who are thrombocytopenic, taking anticoagulant medications, or undergoing surgery.

Shark Cartilage
No scientific evidence supports the use of shark cartilage, despite the fact that is it a popular supplement advertised for treating cancer. For most people, adverse effects from this supplement appear to be minor. But those with a history of hypercalcemia, pregnant women, children, and those with coronary artery disease and blood clotting disorders should not use shark cartilage.

Advice to patients

It is crucial that physicians be aware of any alternative or natural treatments their patients may be using - or thinking about trying - even if it is something that they have used safely in the past. A dietary supplement like vitamin E, for instance, makes good nutrition sense in some cases but can exacerbate medical problems if used during chemotherapy.

Consumers in the United States should also be aware that dietary supplements are not protected by the rigorous standards required of prescription drugs, and there is currently no way to guarantee that a supplement actually contains what its label says it contains.

Source

• Advising patients who seek complementary and alternative medical therapies for cancer. WA. Weiger, M. Smith, H. Boon,  et al., Ann Int Med, 2002, vol. 137, pp. 889--903

Related Links
Alternative Medicine
National Center for Complementary and Alternative Medicine
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