Can herbs help fight prostate cancer? Will vitamins hinder radiation treatment? A few clicks of the mouse at a new National Library of Medicine Web site can help answer these and many more questions about complementary and alternative medicine.

Complementary refers to methods of treatment used in addition to conventional treatments. Examples are drinking peppermint tea to control nausea or having acupuncture for chronic back pain. These methods are not meant to cure disease but to help control symptoms and improve well-being.

The definition of alternative medicine is more fluid and may mean different things to different people. For many, it refers to the use of medicines such as herbs or other traditional (also called "folk") remedies. Alternative medicine also can refer to unproven methods touted as cures for disease that may help, may hurt, or may do nothing.

The new database is offered through a partnership of the National Library of Medicine and the National Center for Complementary and Alternative Medicine (NCCAM), both part of the government's National Institutes of Health. Users can search more than 200,000 references, including some abstracts and some full-text scientific articles within a database devoted exclusively to complementary and alternative medicine.

"A very large and growing percentage of Americans use [complementary and alternative medicine] now," says Stephen E. Straus, MD, director of NCCAM. A 1997 survey showed more than 42% of patients and 47% of doctors used complementary or alternative methods for themselves, spending more than $27 billion in the process, Straus says. "Reliable information is crucial in this context, and we're happy to help offer this excellent tool to provide public access to it," he says.

An expert on complementary and alternative medicine affiliated with the American Cancer Society (ACS) agrees that it is very important to have reliable information on this subject.

"Some [complementary and alternative medicine] use is very beneficial," says David M. Rosenthal, MD, medical director of Harvard University's Zakim Center for Integrative Therapies, and a former president of ACS. "For example, there are herb combinations effective for slowing the growth of prostate cancer in men for whom hormone therapy has stopped working."

"But not all 'alternative' or 'natural' methods are safe," Rosenthal says. "Antioxidant vitamins can interfere with the cancer-cell killing effects of radiotherapy, and ginseng can interfere with some anti-clotting drugs, as examples, so it's vital both for this information to be accessible, and for patients to tell their doctors what they're using."

The complementary and alternative medicine database is very useful for doctors and scientists but for others the database probably should be used to supplement other sources of information, says Rosenthal.

"The database information is mostly from medical and scientific journals, written in scientific language, and may not be easy to translate or decipher for the average person," says Rosenthal. He recommends a book that can help: The American Cancer Society’s Guide to Complementary and Alternative Cancer Methods (hardcover) (paperback), a comprehensive resource guide on hundreds of alternative and complementary methods, based on expert evaluation and written in clear, understandable language.

For more information on complementary and alternative methods related to cancer, call 1-800-ACS-2345.