FIGURE 2. Percentage of patients receiving breast conservation therapy as a function of geographic region. (Percentage was calculated as the proportion of the total number of patients receiving either breast conservation or mastectomy.) NE, New England; MA, mid-Atlantic; SA, south Atlantic; ENC, east north central; ESC, east south central; WNC, west north central; WSC, west south central; M, mountain; P, Pacific. Data from the study by Osteen et al²⁸ represent histologically mixed AJCC stage I and II patients. Data from the study by Albain et al²⁹ represent a node-negative subsample of histologically mixed AJCC stage I and II patients.