Cancer registries have been part of the public health system in the U.S. since before World War II. They serve many purposes: not only do they aid the collection of statistics so that physicians can gauge how the battle against cancer is going, but they can help pinpoint "cancer clusters" that may be caused by environmental factors.

Virtually every state in the U.S. has a registry of cancer cases, under a national surveillance system run by the Centers for Disease Control and Prevention (CDC). This system has been dealing - for the most part successfully - with patient privacy issues for decades. Cancer registries often share medical data while restricting access to information about patient identity.

Now the hospitals in the federal Veterans Affairs (VA) system are saying they will not share cancer data with state registries unless the states sign restrictive agreements. The VA says it is protecting patient privacy. For now, the VA seems to have the upper hand, since states can not force a federal institution to obey state law, according to an Oct. 10 story in the New York Times.

• "States and V.A. at Odds on Cancer Data," [2] New York Times, October 10, 2007, by Gina Kolata.