For several years, clinicians and computer scientists in the U.S. and abroad have been trying to improve cancer care--from diagnosis to treatment--by building vast, interconnected databases full of patient information. They call these repositories "medical grids" and envision the day when a physician in Strasbourg or New Delhi can see, for example, that an indecipherable image of a patient's lung is very similar to that of a San Francisco patient, whose case history could inform the decision to perform a biopsy.

These nascent databases include not only patients' medical histories, including such data as MRIs and CT scans, but also information about how they have responded to drugs. But the benefits of these under--construction grids have been slow to come, partly because of technical problems and partly because federal privacy rules make data sharing difficult. Now, a National Cancer Institute project could test a multihospital system for comparing lung cancer images as early as this year--a clear move toward putting grids to use.