CAM/drug Interactions Put Cancer Patients At Risk, Australia

An increasing number of cancer patients are using complementary and alternative medicine (CAM) without their physicians' knowledge, putting them at risk of adverse interactions with conventional medicine, according to a review published today (24 March 2011) in Cancer Forum.


Professor Stephen Clarke, from the Faculty of Medicine at the University of Sydney, claimed there had been a significant increase in CAM use in the last 15 years, with studies indicating use in cancer patients now exceeded 80 per cent, of whom more than half (57 per cent) failed to tell their physicians.


"Not surprisingly CAM is big business," said Professor Clarke. "In the US alone, it has been estimated that cancer patients spend over US$30 billion in out-of-pocket expenses on CAM."


Professor Clarke said while use of CAM with conventional medicine often had no or minimal effects, in systemically administered herbal medicine and conventional treatments, there were "significant risks of adverse drug interactions" which could result in either "increased drug toxicity or therapeutic failure".


St John's wort, for example, had been shown when co-administered with anti-cancer drug imatinib (Glivec), caused the drug to be cleared from the body 43 per cent faster, which could produce reduced efficacy. Other herbs were likely to delay the clearance of other cancers drugs, resulting in more side-effects. "However, in many cases we just don't know if there is an interaction."


Professor Clarke urged physicians to be more proactive in obtaining complete medication histories, including herbal use, in all patients receiving cancer chemotherapy.


The wide-ranging Forum on 'Complementary and alternative medicine' includes papers on:


- Overview of complementary and alternative medicine (Ian Olver)


- Botanical products in the 21st century (Monica Robotin)


- Psychology of complementary care in cancer (Bogda Koczwara, Lisa Beatty)


- Educating about complementary and alternative medicine (Craig Hassad)


- Interaction of CAM with conventional anti-cancer medicine (Stephen Clarke, Andrew McLachlan)


- Researching complementary and alternative therapies (Haryana Dhillon)


- Prayer as a complementary therapy (Hayley Whitford, Ian Olver)


- Integrating complementary and convention medicine (Carlo Pirri)


- Family and complementary and alternative medicine (Jakline Eliott, Nadje Klafke)


- Patients' perceptions of complementary and alternative medicine (Vivienne O'Callaghan).