A UK cancer expert has said it is time to protect patients from 'vile and cynical exploitation' by the alternative medicines industry.

According to Prof Jonathan Waxman of Imperial College London, an estimated 80% of patients with cancer take a complementary treatment or follow a dietary programme to help treat their disease.

Yet the rationale for the use of many of these approaches is obtuse. In fact, one might even be tempted to describe them as misleading, he wrote in the British Medical Journal.

He said that the claims made by companies to support the sales of such products may be 'overtly and malignly incorrect' and in many cases, the products may be doctored by chemicals borrowed from the conventional pharmaceutical industry. However these products are not subject to the testing of pharmaceuticals because they are classified as food supplements.

He believes that the reason patients take alternative medicines and disregard science is because 'complementary therapists offer something that doctors cannot offer - hope'.

"If you eat this, take this, avoid this and really believe this, then we can promise you sincerely that you will be cured. And if the patient is not cured, it is the patient who has failed, not the alternative therapy. The patient has let down the alternative practitioner and disappointed his family who have encouraged his treatment", Prof Waxman said.

He pointed out that as well as the complementary medicines they take, many patients will have changed their diets in order to try to cure their cancers. But while there is a strong dietary basis to the development of cancer, 'once the disease has been diagnosed, no change in diet will lead to any improvement in cancer outcomes'.

He said the reason why some patients change their diet is to take back some control of a situation that is entirely out of their control. For others, it is because of the pressure put on them by families, friends or vested interest groups to 'go organic'.

Prof Waxman said it is now time to focus 'on a particularly vulnerable section of our society and do something to limit the exploitation of our patients'.

"Reclassify these agents as drugs - for this is after all how they are marketed - and protect our patients from vile and cynical exploitation. The current EU initiative to bring forward legislation on this matter is welcomed", he added.