Bernstein and Grasso present a survey of the use of complementary and alternative medicine (CAM) by cancer patients. Like many such surveys, they report a high prevalence of CAM use. What is of concern in their findings, however, is the widespread use of modalities that may interact with conventional cytotoxic therapy. This observation is particularly worrisome given that the surveyed patients were largely in the first year after diagnosis, and thus were likely to have been using CAM therapies concurrently with conventional treatment.Interactions Between CAM and Conventional Treatment
Nearly half of the patients surveyed by Bernstein and Grasso were using herbal (or "botanical") medicine. Botanical agents are pharmacologically active, particularly with respect to liver metabolism. When a botanical slows or speeds the metabolism of a chemotherapeutic agent, increased toxicity or lowered efficacy may result. St. John’s wort is the best known of several botanical treatments that interact with enzymes in the cytochrome P450 family, in particular, CYP3A4. Experimental data show reduced concentrations of indinavir(Drug information on indinavir) (Crixivan) resulting from the use of St. John’s wort. Decreased levels of chemotherapy agents metabolized by CYP3A4, such as the taxanes, have not been demonstrated empirically but remain a possible concern.
It has also been shown that pretreatment of cancer cells with botanical agents may lower their sensitivity to chemotherapy. For example, pretreatment of colon cancer lines with berberine(Drug information on berberine) markedly reduces paclitaxel(Drug information on paclitaxel) (Taxol)-induced apoptosis and cell-cycle effects. The apparent mechanism of action is upregulation of the multidrug-resistance transporter, pgp-170. Berberine is the main constituent of huanglian, a botanical medicine with in vitro antiproliferative activity against tumor lines.
A further mechanism of interactions between CAM and conventional cancer treatment concerns antioxidants. The activity of radiotherapy and of many chemotherapy drugsincluding the alkylating agents, anthracyclines, and podophyllum agentsdepends, at least in part, on the production of free radicals. Many dietary supplements (such as vitamin C) are strong antioxidants, and some botanicalsfor example, garlic and ginsenghave marked antioxidant properties. Concurrent administration of antioxidant supplements or botanical products may reduce the efficacy of radiotherapy and of chemotherapy agents that act by producing oxidative damage.
In looking at the tables in the Bernstein/Grasso article, it seems likely that more than half of the cancer patients surveyed were using a CAM therapy that, in theory at least, could either reduce the effectiveness or increase the toxicity of conventional therapy. This possibility is clearly of great concern. There is a need for greater public and professional awareness of the risks associated with the use of botanical and dietary supplements by cancer patients. Research to identify and define such risks more precisely is also indicated.The Problem of Alternative Medicine
Bernstein and Grasso explicitly surveyed respondents’ use of several "alternative" cancer treatments, including Gerson therapy and the Hoxsey method. It is not surprising that no respondent appeared to have used these modalities. Alternative therapies are, by definition, used instead of conventional medicine. For example, the "Gonzalez" regimen involves diet, vitamins, enzymes, and enemas to treat cancer. An unusual form of hair analysis is used to guide treatment. The originator of the technique has stated that "You don’t do chemotherapy and Gonzalez. You do one or the other."
Any survey (such as the one described in the article) that interviews patients who present to a conventional cancer center will fail to identify those who have turned to alternative medicine. The only methods capable of identifying such patients involve sampling directly from alternative cancer practices (see, for example, the seminal study by Cassileth et al) or sending questionnaires to the homes of patients identified through cancer registries (see the study by Rees et al). These methods have not been applied in the United States recently. The number of patients currently leaving conventional care to subscribe solely to alternative cancer treatments is not well characterized.Complementary Therapies and Supportive Care
Bernstein and Grasso report that a significant proportion of cancer patients use complementary therapies such as massage (1 in 5 respondents) and relaxation techniques (1 in 3 respondents). These modalities are popular among cancer patients because they address the psychological and physical symptoms, such as anxiety and pain, that commonly result from cancer and its treatment.
Complementary therapies are increasingly available as part of the supportive services offered at conventional cancer centers. For example, a support program offered at the Carol Franc Buck Breast Care Center of the University of California, San Francisco/Mt. Zion, includes meditation and yoga. At Memorial Sloan-Kettering Cancer Center, acupuncture, massage, and relaxation therapies are available both on the inpatient wards and at a special outpatient center.Conclusions
It may be time for surveys of CAM in cancer to separate "complementary" from "alternative" medicine. Is taking shark cartilage to cure cancer really the same sort of behavior as having a massage to treat pain and anxiety? Probably not, and surveys should avoid treating them as such. In terms of cost, avoidance of proven treatment, side effects, and interactions with conventional medicine, alternative cancer therapy is vastly more problematic than complementary therapy. Further sociologic research should therefore focus on the problem of alternative medicine. Research that relies on patients visiting conventional cancer centers will not include patients who have abandoned conventional care to seek alternative cures. Researchers need to find creative ways to identify such patients and describe their behavior.