BioEd Online

One in ten websites offering information on alternative cancer therapies give advice that could harm patients, a recent study suggests.

People need to be aware that such websites are not necessarily benign and they should seek out responsible, independent advice about complementary medicines, warns Edzard Ernst of the Peninsula Medical School, run by the universities of Exeter and Plymouth, who led the study.

Up to 55% of the Internet's 600 million users gather medical information from it. Patients with life-threatening diseases, such as cancer, often use the web to seek out alternative therapies, but with over half a million sites offering advice, the quality of that information varies greatly.

To investigate the likely consequences of patients relying on such websites, Ernst's team surveyed the 32 most popular sites offering advice on 'alternative' or 'complementary' medicine and cancer. Their results can be found in the Annals of Oncology¹.

In total, the sites touted 118 cancer 'cures', such as shark cartilage and mistletoe, and 59 cancer 'preventions', including green tea and flaxseed, also known as linseed. But none of these treatments have been scientifically proven to work, says Ernst.

Shark cartilage was the most recommended alternative cancer 'cure'. A preliminary human study has suggested that Neovastat, a product derived from cartilage, can lengthen the lives of patients with a type of kidney cancer². But the research needs to be repeated with larger numbers, and the only published clinical study of a shark cartilage treatment for cancer failed to find any positive effects³.

Because such preparations have not been scientifically tested, their benefits are questionable and it is possible that they might interact adversely with conventional treatments.

Worse still, three of the websites (HEALL, HealthWorld Online and worldwidehealthcenter.net) overtly discouraged patients from using conventional cancer care, such as chemotherapy and radiotherapy. One of the sites also dissuaded its readers from taking doctors' advice. "These websites are a risk to cancer patients," says Ernst.

Not all bad

Good websites do exist, and the majority of those tested provided useful and reliable information. Two sites, Quackwatch and Bandolier, stood out for the quality of the information they provide, says Ernst.

He hopes to raise public awareness about the usefulness of online information. He suggests that the major cancer organizations should investigate websites offering cancer-related information and issue a recognized 'seal of approval' to help patients sift good advice from bad.

In the meantime, Ernst stresses the need for patients to be vigilant, and to be aware that some websites may have a financial motive for promoting certain alternative therapies. "My basic advice is: if it sounds too good to be true, it probably is too good to be true."

"There is a confusing amount of information about 'alternative' cancer cures available on the Internet," says cancer expert Julie Sharp of Cancer Research UK. "Many of these have no clinical or scientific basis and so it is vitally important that patients seek advice from their doctors."