
EVANSTON, Indiana-Analysis of traditional factors that correlate with choice of mastectomy or breast-conserving surgery failed to explain the significantly higher mastectomy rates in the United States compared to the United Kingdom seen in the international Arimidex (anastrozole), Tamoxifen, Alone or in Combination (ATAC) trial. ATAC investigator Gershon Y. Locker, MD, noted the striking difference "in the mastectomy rates between the two largest accruing nations in ATAC-the United Kingdom with a 42% mastectomy rate and the United States with a 51% mastectomy rate. This is a 21% increased risk of having a mastectomy if enrolled in the United States compared to the United Kingdom."

