WASHINGTON, D.C.: Is everything French good for you? First researchers found that red wine is good for the heart. Now a new study has found a substance in grapes that may prevent cancer. Researchers have found that a substance in grapes called resveratrol can help keep cells from turning cancerous and inhibit the spread of cells that already are malignant. Resveratrol has been tested only in cell cultures and laboratory animals, but researchers say the results offer the promise eventually of developing pills that will defend against cancer. Hopefully, researchers are even now examining the health benefits of pate and brie.