Researchers from the psychiatry department at the University of California, San Diego, reviewed 194 Internet sites containing information about three complementary/alternative treatments.
They looked at: floressence, an herbal product used by many cancer patients; amalaki, an herb that's used as part of an Ayurvedic cancer-treatment approach; and selenium, a nonherbal treatment that's often used in complementary cancer treatment.
When they reviewed the Internet sites, the researchers asked themselves whether the treatments were for sale online, whether there were patient testimonials on the sites, whether the treatment was touted as a cancer cure, and whether the treatment claimed to have no side effects.
If they got a "yes" answer to any of these questions, the researchers gave that particular site a "red flag", suggesting that the site's scientific accuracy was questionable.
The report found that more than 90 percent of the Internet sites with information about floressence and amalaki raised at least one red flag. Neither of these products have been subjected to rigorous scientific testing.
In comparison, 23 percent of the sites discussing selenium -- a treatment with some scientific merit --raised at least one red flag.
The majority of sites about selenium, even those with red flags, offered at least some accurate information about selenium use and cancer treatment, the report says.
There were large amounts of vague, inaccurate and anecdotal information on the floressence and amalki sites tagged with multiple red flags by the researchers.
The sites dealing with those products that were free of red flags offered accurate, scientifically based information published in peer-reviewed journals or provided by organizations such as the U.S. National Cancer Institute.
The U.S. National Cancer Institute has more about complementary and alternative cancer treatments.