The decreased incidence of invasive breast cancer in the United States seen in 2002 and 2003 did not extend to women of African ancestry, researchers from the University of Chicago Medical Center report at the 2008 annual meeting of the American Association for Cancer Research in San Diego.Breast cancer incidence rates in U.S. women over 50 declined sharply during 2002 and 2003. But this decline, the researchers report, was confined to Caucasians.