Doctors giving patients high doses of cancer-fighting cells taken from their tumors have turned back lethal skin cancer at a rate nearly four times greater than by using chemotherapy, scientists reported Thursday.

The work is the latest development in a new strategy of revving up the body's own weapons to stop cancer. However, experts say this approach is still highly experimental, and no one knows whether it will turn out to be a practical way to fight disease.Only one of the 20 patients treated has had a lasting remission after more than a year, but doctors were encouraged because most of the patients had at least partial responses.

The study was directed by Dr. Steven A. Rosenberg, who has developed the strategy known as adoptive immunotherapy at the National Cancer Institute. In earlier attempts, he used a natural chemical called interleukin-2 to prime cancer-fighting cells taken from the blood. These cells were then turned loose inside the body to hunt for cancer.