Cancer patients who are looking for herbs, vitamins, or other unconventional therapies on the Internet have a new tool to help them avoid quack cures and bad medical information.

Web users can rate a site with four simple yes-or-no questions designed by the authors of "The Internet for Medical Information About Cancer: Help or Hindrance?" (Psychosomatics, 44:100-103, April 2003). Each "yes" answer is considered a "red flag" -- a warning to users that the Web site is likely to have vague or scientifically inaccurate information. The questions are:

1. Is online purchasing permitted?
2. Are "patient testimonials" available?
3. Is the treatment described as a "cancer cure"?
4. Is the treatment described as "having no side effects"?

To test how well these questions flagged questionable scientific information, lead author Scott Matthews, MD, and colleagues from the University of California, San Diego, Cancer Center searched the Internet for floressence, amalaki, and the mineral selenium. These complementary or alternative compounds are used by some cancer patients.

They reviewed 194 Web sites that mentioned those three substances, some of which included outlandish claims.

"For example, one site with two red flags described how amalaki may be used to treat ’any liver or heart complaints’ and ’is also applied as a paste to the head in mental disorders,’" wrote Matthews, et al.

Study authors checked each site's information about the compounds with peer-reviewed, scientifically accurate medical information. "Over 90% of the sites for floressence and amalaki had at least one red flag," wrote the authors.

While sites with no red flags often provided some scientifically accurate information, those with red flags did not. Instead, they included large amounts of vague and unsubstantiated information.

One site told of a 79-year-old patient with "bowel cancer," who supposedly took "recommended daily doses of Flor-Essence" for six months with "staggering results." It went on to claim that normal appetite and bowel function returned, pain was reduced, and there was a "disappearance of the tumors without medical intervention."

Internet sites fared better when describing the mineral selenium, which is being formally studied for a possible role in preventing prostate cancer. Fewer than 25% of those sites had one or more red flags. And in general, the scientific information about selenium was more accurate, no matter how many red flags a site had.

The sites with accurate information were also more likely to have links to respected scientific organizations such as the National Cancer Institute and the National Center for Complementary and Alternative Medicine.

The authors concluded that, "For cancer treatments that have not been rigorously studied, the red flag criteria offer a rapid way of screening Internet sites for likely scientific accuracy." They went on to suggest that patients avoid sites that raise any "red flags" in response to the four screening questions.

"There is a staggering amount of medical misinformation on the Internet," they wrote.